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Burkett + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Natural History of Cottonmouth Moccasin, Agkistrodon piscovorus (Reptilia) + +Author: Ray D. Burkett + +Release Date: December 15, 2011 [EBook #38308] + +Language: English + +Character set encoding: UTF-8 + +*** START OF THIS PROJECT GUTENBERG EBOOK NATURAL HISTORY OF *** + + + + +Produced by Chris Curnow, Joseph Cooper and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + +</pre> + + +<h2><img src="images/bar_double.png" alt="double bar" height="15" width="100%" /></h2> +<div class="smcap"> + <h2><span class="smcap">University of Kansas Publications</span><br /> + <span class="smcap">Museum of Natural History</span></h2> +</div> +<h2>Vol. 17, No. 9, pp. 435-491, 7 figures in text</h2> +<div class="c7"> + <h2><img src="images/bar_single.png" title="bar" alt="bar" height="15" width="28%" /> October 27, 1966 <img src="images/bar_single.png" title="bar" alt="bar" height="15" width="28%" /></h2> +</div> +<h1>Natural History of Cottonmouth Moccasin,</h1> +<h1>Agkistrodon piscivorus (Reptilia)</h1> +<h3>BY</h3> +<h3>RAY D. BURKETT</h3> +<h2> <span class="smcap">University of Kansas</span><br /> + <span class="smcap">Lawrence<br /> + </span>1966<br /> +</h2> +<hr class="chap" /> +<p><span class="pagenum"><a name="Page_436" id="Page_436">[436]</a></span></p> +<div class="c7"> + <h3> <span class="smcap">University of Kansas Publications, Museum of Natural History</span><br /> + <br /> + Editors: E. Raymond Hall, Chairman, Henry S. Fitch,<br /> + Frank B. Cross</h3> + <h4>Vol. 17, No. 9, pp. 435-491, 7 figures in text<br /> + Published + October 27, 1966 </h4> + <h3> <b> <span class="smcap">University of Kansas</span><br /> + <span style="font-weight: 400">Lawrence</span>, <span style="font-weight: 400">Kansas</span></b><br /> + </h3> + <h5>PRINTED BY<br /> + ROBERT R. (BOB) SANDERS, STATE PRINTER<br /> + TOPEKA, KANSAS<br /> + 1966<br /> + <br /> + 31-4629</h5> +</div> +<p><span class="pagenum"><a name="Page_437" id="Page_437">[437]</a></span></p> +<hr class="chap" /> +<h2><a name="Natural_History_of_Cottonmouth_Moccasin" id="Natural_History_of_Cottonmouth_Moccasin"></a>Natural History of Cottonmouth Moccasin,<br /> + Agkistrodon piscivorus (Reptilia)</h2> +<h4>BY<br /> + RAY D. BURKETT</h4> +<hr class="chap" /> +<h2><a name="CONTENTS" id="CONTENTS"></a>CONTENTS</h2> +<div class="c7"> + <table summary="contents" cellpadding="3" cellspacing="0" width="80%"> + <tbody> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td align="right"><small>PAGE</small></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Introduction</span></td> + <td align="right"><a href="#Page_439">439</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Acknowledgments</span></td> + <td align="right"><a href="#Page_440">440</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Systematic Relationships and Distribution</span></td> + <td align="right"><a href="#Page_441">441</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Description</span></td> + <td align="right"><a href="#Page_444">444</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Color and Pattern</td> + <td align="right"><a href="#Page_444">444</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Scutellation</td> + <td align="right"><a href="#Page_444">444</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Dentition</td> + <td align="right"><a href="#Page_449">449</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Habitat and Limiting Factors</span></td> + <td align="right"><a href="#Page_450">450</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Reproduction</span></td> + <td align="right"><a href="#Page_452">452</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Courtship and Mating</td> + <td align="right"><a href="#Page_452">452</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Reproductive Cycles</td> + <td align="right"><a href="#Page_452">452</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Embryonic Development</td> + <td align="right"><a href="#Page_454">454</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Birth of Young</td> + <td align="right"><a href="#Page_454">454</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Number of Young per Litter</td> + <td align="right"><a href="#Page_454">454</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Population Composition</td> + <td align="right"><a href="#Page_455">455</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Reproductive Potential</td> + <td align="right"><a href="#Page_455">455</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Growth and Development</span></td> + <td align="right"><a href="#Page_456">456</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Size at Birth and Early Growth</td> + <td align="right"><a href="#Page_456">456</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">The Umbilical Scar</td> + <td align="right"><a href="#Page_457">457</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Later Growth and Bodily Proportions</td> + <td align="right"><a href="#Page_457">457</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Shedding</span></td> + <td align="right"><a href="#Page_459">459</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">The Shedding Operation</td> + <td align="right"><a href="#Page_459">459</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Frequency of Shedding</td> + <td align="right"><a href="#Page_460">460</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Food Habits</span></td> + <td align="right"><a href="#Page_461">461</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Methods of Obtaining Prey</td> + <td align="right"><a href="#Page_461">461</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Food and Food Preferences</td> + <td align="right"><a href="#Page_462">462</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Mortality Factors</span></td> + <td align="right"><a href="#Page_465">465</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Natural Enemies and Predators</td> + <td align="right"><a href="#Page_465">465</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Parasites and Diseases</td> + <td align="right"><a href="#Page_465">465</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Miscellaneous Causes of Death</td> + <td align="right"><a href="#Page_466">466</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Behavior</span></td> + <td align="right"><a href="#Page_466">466</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Annual and Diel Cycles of Activity</td> + <td align="right"><a href="#Page_466">466</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Basking</td> + <td align="right"><a href="#Page_469">469</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Coiling</td> + <td align="right"><a href="#Page_469">469</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Locomotion</td> + <td align="right"><a href="#Page_470">470</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Disposition</td> + <td align="right"><a href="#Page_470">470</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Defense and Escape</td> + <td align="right"><a href="#Page_471">471</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">"Head Bobbing"</td> + <td align="right"><a href="#Page_471">471</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Combat Dance</td> + <td align="right"><a href="#Page_472">472</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">The Venom</span></td> + <td align="right"><a href="#Page_473">473</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Properties of the Venom</td> + <td align="right"><a href="#Page_473">473</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Venom Yield and Toxicity</td> + <td align="right"><a href="#Page_473">473</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Susceptibility of Snakes</td> + <td align="right"><a href="#Page_475">475</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">The Bite</span></td> + <td align="right"><a href="#Page_476">476</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Effects of the Bite</td> + <td align="right"><a href="#Page_476">476</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Treatment</td> + <td align="right"><a href="#Page_477">477</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Case History of a Bite</td> + <td align="right"><a href="#Page_479">479</a></td> + </tr> + <tr> + <td align="left"> </td> + <td align="left">Snakebite in the United States</td> + <td align="right"><a href="#Page_480">480</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Summary</span></td> + <td align="right"><a href="#Page_480">480</a></td> + </tr> + <tr> + <td colspan="2" align="left"><span class="smcap">Literature Cited</span></td> + <td align="right"><a href="#Page_485">485</a></td> + </tr> + </tbody> + </table> +</div> +<p><span class="pagenum"><a name="Page_439" id="Page_439">[439]</a></span></p> +<hr class="chap" /> +<h2>INTRODUCTION</h2> +<p>Objectives of the study here reported on were to: (1) learn as + much as possible concerning the natural history and economic + importance of the cottonmouth; (2) determine what factors limit + its geographic distribution; (3) determine the role of the cottonmouth + in its ecological community; and (4) compare the cottonmouth's + life history with that of other crotalid snakes, especially the + kinds that are most closely related to it.</p> +<p>Twenty-five live cottonmouths were kept in the laboratory for + the purpose of studying behavior and fang shedding and for comparison + of measurements with those of preserved specimens. Live + snakes were obtained in Brazoria and Nacogdoches counties, Texas, + from Hermann Park Zoo, Houston, Texas, and from the late Paul + Anderson of Independence, Missouri. Preserved western cottonmouths + were examined for the purpose of determining variation, + distribution, food habits, body proportions, embryonic development, + and reproductive cycles. The cottonmouths examined include: + 221 from Texas; 33 from Arkansas; 22 from Louisiana; 2 + from Illinois; and 1 each from Kansas, Mississippi, and Oklahoma.</p> +<p>In the preparation of this report I have examined all available + literature pertaining to the cottonmouth and have drawn from + these sources for comparative or additional material. Some of the + more noteworthy contributions to knowledge of the cottonmouth + are the general accounts of the life history by Allen and Swindell + (1948), Barbour (1956), and Wright and Wright (1957); the publications + by Gloyd and Conant (1943) concerning taxonomy; + Klimstra (1959) concerning food habits; and Allen (1937), Parrish + and Pollard (1959), Swanson (1946), and Wolff and Githens + (1939b) concerning the venom. Numerous other publications, + although brief, contain worthwhile contributions. Also of special + interest as a source of material for comparison of cottonmouths with + other crotalids are the works of Fitch (1960) on the copperhead and + of Klauber (1956) on the rattlesnakes.</p> +<p>The cottonmouth has been well known for nearly 200 years. + Wright and Wright (1957) listed the following vernacular names + that are applied to the cottonmouth: black moccasin, black snake, + blunt-tail moccasin, congo, copperhead, cottonmouth water moccasin, + cotton-mouthed snake, gapper, highland moccasin, lowland + moccasin, mangrove rattler, moccasin, North American cottonmouth + snake, North American water moccasin, North American + water viper, pilot, rusty moccasin, salt-water rattler, stubtail, stump <span class="pagenum"><a name="Page_440" id="Page_440">[440]</a></span> (-tail) moccasin, stump-tail viper, swamp lion, Texas Moccasin, + trapjaw, Troost's moccasin, true horn snake, true water moccasin, + viper, water mokeson, water pilot, water rattlesnake, and water + viper.</p> +<p>Some of the names listed above are based upon superstition and + folklore prevailing in pioneer times, and others are based upon the + behavior or appearance of the snake at various ages. Names like + "stump-tail moccasin" are derived from the appearance of females + which have short tails or snakes that have lost part of the tail. + Names like "gapper" and "trapjaw" came to be applied because + of the habit of the snake's lying with its mouth open when approached. + The name "cottonmouth" also was derived from this + behavior, although the lining of the mouth is whitish in most other + snakes. The term "rattlesnake" may have come from the fact that + the cottonmouth vibrates its tail vigorously when nervous as do + many other snakes, or it may have been confused with rattlesnakes. + Because of the general public's fear of snakes and their reluctance + to learn to discriminate between the poisonous and harmless species, + numerous kinds of snakes seen in or near water have been called + moccasins. The general appearance, pugnacious behavior, and + whitish mouth of water-snakes (<i>Natrix</i>) have earned them a bad + reputation. In fact, a great majority of the "cottonmouths" reported + in many areas are found to be water-snakes.</p> +<p>The cottonmouth is economically important mainly because of + the injurious or fatal effects of its bite and the psychological effect + that its actual or suspected presence has upon many persons. The + species eats a wide variety of prey items and helps to prevent overabundance + of certain kinds of organisms. The venom has been + used in the therapeutic treatment of blood clots owing to its anticoagulant + properties (Didisheim and Lewis, 1956). It also is employed + in the treatment of haemorrhagic conditions and rheumatoid + arthritis, as well as in the production of antivenin (Allen and + Swindell, <i>op cit.</i>:13). None of these uses of venom has become + widely accepted, and its value is questionable.</p> +<hr class="chap" /> +<h2>ACKNOWLEDGMENTS</h2> +<p>For guidance in the course of my study, I am especially indebted to Professor + Henry S. Fitch. For suggestions concerning the preparation of the + manuscript, I thank Professor E. Raymond Hall. I am grateful to my wife, + Janis, for her invaluable assistance and for typing the manuscript.</p> +<p>For use of specimens in their care, I thank Professors William E. Duellman, + University of Kansas; Robert L. Packard, formerly of Stephen F. Austin State + College; W. Frank Blair, University of Texas; and William B. Davis and</p> +<p><span class="pagenum"><a name="Page_441" id="Page_441">[441]</a></span></p> +<p>Richard J. Baldauf, Texas Agricultural and Mechanical College. Mr. John + E. Werler of the Hermann Park Zoo, Houston, Texas, contributed live individuals; + Mr. Richard S. Funk contributed information on the birth of a brood + of cottonmouths; and Dr. Henry M. Parrish contributed information on the + incidence of snakebite. To numerous other persons at leading museums + throughout the United States for information on the cottonmouths in their + collections, to all who helped with the field work in various ways, and to + others at the University of Kansas for their help and suggestions I am grateful.</p> +<hr class="chap" /> +<h2>SYSTEMATIC RELATIONSHIPS AND DISTRIBUTION</h2> +<p>Snakes of the genus <i>Agkistrodon</i> are relatively primitive members of the + Crotalidae, which is one of the most specialized families of snakes. A majority + of the pit-vipers are found in the Americas, but close relatives are found from + extreme southeastern Europe through temperate Asia to Japan (<i>A. halys</i>) and + southeastern Asia including Indonesia (<i>Agkistrodon</i> and <i>Trimeresurus</i>). Familial + characters include: vertical pupil of the eye; facial pit present between + the preoculars and loreal; scales usually keeled; short, rotatable maxilla bearing + a large hollow fang; toothless premaxilla; chiefly hematoxic venom; and undivided + anal plate.</p> +<p>The genus <i>Agkistrodon</i> includes about nine species in the Old World and + three in North and Central America. Some of the primitive characters of the + genus are: head covered with nine enlarged shields or having the internasals + and prefrontals broken up into small scales; subcaudals on proximal part of + tail undivided; fangs relatively short; tail lacking rattles. In one species, <i>A. + rhodostoma</i>, the scales are smooth; and the female is oviparous and guards her + eggs until they hatch. Other species have keeled scales and are ovo-viviparous.</p> +<p>There is little paleontological evidence illustrating evolution of the cottonmouth + or for that matter of crotalids in general. Brattstrom (1954) summarized + the current knowledge of fossil pit-vipers in North America. The few fossils + found of the cottonmouth are from Alacha, Brevard, Citrus, Levy, Pasco, and + Pinellas counties, Florida (Brattstrom, <i>op. cit.</i>:35; Auffenberg, 1963:202). All + are of late Pleistocene Age and well within the present geographic range of the + cottonmouth.</p> +<p>Of crotalid genera only <i>Agkistrodon</i> occurs in both the Old World and the + New World, suggesting that this genus is relatively old. Schmidt (1946: + 149-150) mentioned several other closely related groups of animals found in + both eastern Asia and eastern North America, including the reptilian genera: <i>Natrix</i>, <i>Opheodrys</i>, <i>Elaphe</i>, <i>Ophisaurus</i>, <i>Leiolopisma</i> (= <i>Lygosoma</i>), <i>Eumeces</i>, <i>Clemmys</i>, <i>Emmys</i>, and <i>Alligator</i>. Of the groups of animals now confined to + these two regions the most important are the cryptobranchid salamanders, the + genus <i>Alligator</i>, and the spoon-bills (<i>Psephurus</i> in China and <i>Polyodon</i> in the + Mississippi drainage). Fossil evidence for these groups indicates that existing + forms common to eastern Asia and eastern North America are remnants of a + late Cretaceous or early Tertiary Holarctic fauna which was forced southward + as the climate became gradually cooler to the north. "Other clues suggest + that both <i>Agkistrodon</i> and <i>Trimeresurus</i> (<i>Bothrops</i>) moved from Asia to + America, one of these presumably giving rise to the rattlesnakes." (Darlington, + 1957:228).</p> +<p><span class="pagenum"><a name="Page_442" id="Page_442">[442]</a></span></p> +<p>The named, American kinds of <i>Agkistrodon</i> currently are arranged as three + species: the copperhead, the cantil and the cottonmouth. The copperhead + (<i>A. contortrix</i>) is divided into four subspecies, all of which are terrestrial. This + species occurs from southern New England to eastern Kansas and along the + Atlantic and Gulf Coastal plains, exclusive of peninsular Florida and the delta + of the Mississippi River in Louisiana. It extends southwest from Kansas through + the Edwards Plateau of west-central Texas. Isolated populations occur in the + Chisos and Davis mountains of Trans-Pecos Texas. The cantil or Mexican + moccasin (<i>A. bilineatus</i>), probably the nearest relative of the cottonmouth + (<i>A. piscivorus</i>), is divisible into two subspecies and occupies a nearly complementary + range from Mexico south to Nicaragua. The cottonmouth occurs + throughout the coastal plains of the southeastern United States, usually at + altitudes of 500 feet or less. Two subspecies are recognized, the eastern <i>A. p. + piscivorus</i> and the western <i>A. p. leucostoma</i>. A revision of the genus is underway + by Professor Howard K. Gloyd.</p> +<p>The basic pattern and various behavioral traits are common to all three + species. The young are more nearly alike in appearance than adults, the + copperhead and the cottonmouth being easily confused. Adults differ in + color, size, body proportions, habitat, and habits. In range and habitat preference + the cottonmouth more closely resembles the southern subspecies of + the copperhead, <i>A. c. contortrix</i>, which is usually found in lowlands, near + swamps and streams, but seldom in water.</p> +<div class="figcenter" style="width: 600px;"> <img src="images/i_442.jpg" alt="Fig. 1. Geographic range of the cottonmouth" height="434" width="600" /> <span class="caption">Fig. 1.</span> </div> +<p><span class="smcap">Fig. 1.</span> Geographic range of the cottonmouth, showing marginal and near-marginal + records, based largely upon maps by Gloyd and Conant (1943:165) + and Conant (1958:336) but including additional records. The more important + of these records (from east to west) are discussed in the following paragraphs. + Crosshatching indicates the area of intergradation between the eastern and + western subspecies. Old records, indicated by dates, and their sources are as + follows: 1850's and 1891—U. S. National Museum numbers 4263 and 32753 + respectively; 1897—Hurter (1897); and 1895—Stejneger (1895:408).</p> +<p><span class="pagenum"><a name="Page_443" id="Page_443">[443]</a></span></p> +<p>The northernmost record for the eastern subspecies is in the Petersburg area, + Prince George County, Virginia (Anon., 1953:24). A sight record (Hickman, + 1922:39) near Bristol, West Virginia, probably was based on a water-snake + (<i>Natrix</i> sp.), since the stream in which the snake was seen flows north into the + Ohio River rather than southeast through Virginia. In North Carolina the + most inland record is from the Neuse River, six to eight miles east of Raleigh + (Stejneger, 1895:408). Neill (1947:205) reported a population in the vicinity + of Dry Fork Creek on the boundary line of Wilkes and Oglethorpe counties, + Georgia. Distribution of cottonmouths in Florida is statewide, including the + Keys and other offshore islands.</p> +<p>The ranges of the two subspecies, <i>piscivorus</i> and <i>leucostoma</i>, meet near the + eastern border of Mississippi. <i>A. p. piscivorus</i> has been reported from Tishomingo + County to the Gulf and east of the Loess Bluff area in central Mississippi, + and <i>A. p. leucostoma</i> has been reported from this area westward. A few + specimens from along the Coast indicate intergradation (Cook, 1962:33) between + the two subspecies.</p> +<p>Barbour (1956:33) reported one specimen from Cypress Creek, in the Green + River drainage, Muhlenberg County, Kentucky, and stated that suitable habitat + can be found in several areas east of Kentucky Lake. Hence, cottonmouths + may have entered this area via the Ohio River. Stejneger (<i>loc. cit.</i>) + reported the species in the Wabash River at Mount Carmel, Wabash County, + Illinois, and mentioned a former occurrence at Vincennes, Knox County, + Indiana; but there are no recent records at these localities. Hurter (1897) + reported having seen cottonmouths in Illinois, opposite St. Louis; Smith (1961:265) + believes that this and a population in Monroe County, Illinois, are + isolated relicts, since no specimens have been found within 50 miles to the + south of Monroe County. The specimens reported by Anderson (1941:178; + 1945:274) near Chillicothe (three miles southwest and seven miles northwest, + respectively), Livingston County, Missouri, also are thought to represent a relict + population. Hall and Smith (1947:453) reported one specimen from Jasper + County, Missouri, in the Spring River which flows through extreme southeastern + Kansas and into Oklahoma and another in the Neosho River at Chetopa, Kansas. + Both of these specimens were taken after a flood, and no additional + specimens have been taken in this region. Nevertheless, sufficient habitat is + probably available along the Neosho and Verdigris rivers in the southeastern + part of Kansas.</p> +<p>In Texas the cottonmouth has penetrated marginal habitat perhaps farther + than anywhere else in its range. Formerly it was thought to be limited to the + country east of the Balcones Escarpment (Smith and Buechner, 1947:8), but + semiarid areas of the state have been invaded primarily via the Colorado and + Brazos River systems up to altitudes of 2300 feet. Two additional specimens + are said to have been collected along the Rio Grande. Dr. Howard K. Gloyd + (<i>in litt.</i>) stated that the specimen reported from Eagle Pass, Maverick County, + is believed to have been taken in the 1850's; and the one said to have come + from the mouth of the Devil's River is actually marked "near Santa Rosa, + Cameron County, September 30, 1891." No additional specimens have been + taken in that area; and the range now probably extends no farther south than + Corpus Christi, Texas. Brown's (1903:554) knowledge of the extension of + the range of the cottonmouth west of longitude 98° is probably based upon + the records along the Rio Grande reported in the nineteenth century.</p> +<p>Three extensions of the known range in Texas are reported herein. One + specimen was captured by Mr. Harry Green (HWG 346) along the San Saba + River, 8.1 miles west of Menard, Menard County. The other two specimens + (KU 84375 and 84376) were taken by the late Paul Anderson one and one-half + miles north of Pecan Crossing, South Concho River, Tom Green County, + and one mile west of Mertzon, Irion County.</p> +<p>In the hypsithermal period following Pleistocene glaciation, cottonmouths + gradually moved northward occupying areas beyond their present range. The + distributional records since the 1850's and the apparent relict populations now + in existence indicate that the range of this species has since receded.</p> +<hr class="chap" /> +<p><span class="pagenum"><a name="Page_444" id="Page_444">[444]</a></span> </p> +<h2>DESCRIPTION</h2> +<h3>Color and Pattern</h3> +<p>Color predominantly brown, ranging through pale reddish-brown or dark + reddish-brown, brownish-green, to almost black; 10 to 17 irregular dark brown + bands on paler brown ground color; young paler (some nearly salmon pink), + retaining a vivid pattern throughout first year; pattern of most individuals + nearly obliterated by third year; brilliance and dullness of predominant color + correlated with molting cycle (skin especially bright and shiny immediately + following shedding; tip of tail yellowish in juveniles; posterior part of venter + and tail uniformly black in some adult individuals, especially females; secondary + sexual differences in dorsal coloration, such as found in copperhead by Fitch + (1960:102), not noted.</p> +<p>The eastern subspecies, <i>A. p. piscivorus</i>, has the more brilliant pattern in + which the centers of the dark cross-bands are invaded by the ground color. + The cross-bands are slightly constricted in the mid-line and may or may not be + bilaterally symmetrical. One-half of the cross-band may be displaced anteriorly + or posteriorly to a slight degree or may even be completely absent. From one + to several dark spots may be present within the cross-bands.</p> +<p>The western subspecies, <i>A. p. leucostoma</i>, has a comparatively dull pattern + in which the ground color does not invade the center of the cross-bands. In + many instances the bands are outlined by white scales, as in the Mexican + moccasin (this character is not so prominent in <i>A. p. piscivorus</i> because of + the paler ground color). A large, dark blotch usually occurs at the base of + the cross-band and may completely cross the ventral scales. The characteristic + variations found in <i>piscivorus</i> are also present in <i>leucostoma</i>.</p> +<p>The number of bands is often difficult to count because of the dark color + of some specimens. Gloyd and Conant (1943:168) reported averages of 12.5 + (11 to 16) and 12.2 (10 to 16) in males and females, respectively, of <i>leucostoma</i> and ranges of 10 to 17 for males and 10 to 16 for females with averages + of 13 in both sexes of <i>piscivorus</i>. On 20 specimens of <i>leucostoma</i> from Texas + the average number of bands was 12.7 (11 to 15). If the number of bands + differed on the two sides of an animal, the total number of the two sides was + divided by two.</p> +<blockquote> + <h3>Scutellation</h3> +</blockquote> +<p>The scutellation of the cottonmouth closely resembles that of the other + species of <i>Agkistrodon</i>. For example, the nine cephalic shields are characteristic + of most species of <i>Agkistrodon</i>, as well as most other primitive crotalids and + viperids, and most colubrids. Most individuals have an additional pair of large + scales behind the parietals.</p> +<p>The numbers of postoculars, supralabials, and infralabials are variable. On + either side the postoculars (three in most specimens) are reduced to two in + some specimens. The supralabials (eight in most specimens) frequently vary + (usually on one side only) from seven to nine. The number of infralabials is + somewhat more variable than the number of supralabials, the usual number + being 11, but 10 is also common; 8, 9, and 12 are more rare (Table 1). In + 102 snakes in which these characters were examined, four different combinations + of supralabials and seven combinations of infralabials were found. Both + characters together yielded 16 combinations, considering only the actual number + of scales and not taking into account the side of the head on which they + occurred (Table 2). The combinations found in a brood of seven young from + Houston, Texas, are shown in Table 3 to illustrate the variability of this character. + Gloyd and Conant (1943:168) found a variation of 6 to 11 (8) and 7 + to 9 (8) supralabials and 8 to 13 (11) and 8 to 12 (10.4) infralabials in + samples of 301 <i>leucostoma</i> and 119 <i>piscivorus</i>, respectively (numbers in + parentheses represent average). Also of interest is the variability of the scales + themselves. In one instance a scale was found that had not completely divided. + In another specimen the last supralabial and last infralabial were one scale + that completely lined the angle of the jaw. Instances of one scale almost <span class="pagenum"><a name="Page_445" id="Page_445">[445]</a></span> crowding out another were common. In still other instances one or two + supralabials were divided horizontally into two scales. Individual variation + rather than geographical variation occurs in these characters.</p> +<p style="text-align: center"> </p> +<p style="text-align: center"> TABLE 1.—Frequency of Occurrence of Various Numbers of Supralabial and<br /> + Infralabial Scales in 102 Cottonmouths.</p> +<div class="c7"> + <table summary="scale frequency" style="border-width: 1px; border-bottom-style: solid;" + cellpadding="3" cellspacing="0" width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Number of scales</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Specimens having number on both sides</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Specimens having number on one side</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Total</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center">Percentage</td> + </tr> + <tr> + <td colspan="5" align="center">Supralabials</td> + </tr> + <tr> + <td style="border-width: 1px; border-top-style: solid;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 11</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 24</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 35</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 25.2</td> + </tr> + <tr> + <td align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 64</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 27</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 91</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 65.5</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 9</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 0</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 2.2</td> + </tr> + <tr> + <td colspan="5" align="center"> Infralabials</td> + </tr> + <tr> + <td style="border-width: 1px; border-top-style: solid;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 0</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 1.5</td> + </tr> + <tr> + <td align="center"> 9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 13</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9.6</td> + </tr> + <tr> + <td align="center"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 32</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 44</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 32.4</td> + </tr> + <tr> + <td align="center"> 11</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 53</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 22</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 75</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 55.1</td> + </tr> + <tr> + <td align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.5</td> + </tr> + </tbody> + </table> +</div> +<p> </p> +<p style="text-align: center"> TABLE 2.—Numbers of Supralabials and Infralabials of 102 Cottonmouths.</p> +<div class="c7"> + <table summary="number" cellpadding="3" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Number of<br /> + individuals</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Number of <br /> + supralabials</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Number of <br /> + infralabials</td> + </tr> + <tr> + <td align="center"> 37</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + </tr> + <tr> + <td align="center"> 15</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10-11</td> + </tr> + <tr> + <td align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + </tr> + <tr> + <td align="center"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10-11</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9-10</td> + </tr> + <tr> + <td align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + </tr> + <tr> + <td align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9-10</td> + </tr> + <tr> + <td align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10-12</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8-9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8-9</td> + </tr> + <tr> + <td align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 8-9</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 10-11</td> + </tr> + </tbody> + </table> +</div> +<p>The dorsal scales of cottonmouths are strongly keeled except that those of + the two lower scale-rows on each side are weakly keeled. Also they are + slightly larger than the others. Two apical pits are present on each dorsal + scale. The shape of the scales and number of scale rows vary depending upon + the position on the body. Scales on the neck are considerably smaller than + those elsewhere on the body and are arranged in two or three more rows than + those at mid-body. The skin in the region of the throat, neck, and fore-body is <span class="pagenum"><a name="Page_446" id="Page_446">[446]</a></span> especially elastic and allows the swallowing of large prey. Posteriorly from the + mid-body the scales decrease in size and become more angular, those on the + tail tending to be rhomboidal and wider than long. In the region of the anus + the number of scale rows diminishes rapidly, leaving only 12 to 14 rows at the + base of the tail and only three rows immediately ahead of the tail tip. The + tail ends in a spine composed of two scales: one scale covers the bottom, lower + parts of the sides, and tip of the spine; and a shorter dorsal scale covers the + top and upper parts of the sides of the basal two-thirds of the spine. The + spine of embryos and young cottonmouths is blunt, but is pointed in most + adults.</p> +<p style="text-align: center"> </p> +<p style="text-align: center"> TABLE 3.—Variation in Numbers of Supralabials and Infralabials in a Brood<br /> + of Seven Cottonmouths.</p> +<div class="c7"> + <table summary="variation" cellpadding="3" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Number of<br /> + individuals</td> + <td style="border-top-style: double; border-width: 4px 1px 1px; border-bottom-style: solid; border-left-style: solid;" align="center"> Number of<br /> + supralabials</td> + <td style="border-top-style: double; border-width: 4px 1px 1px; border-bottom-style: solid; border-left-style: solid;" align="center"> Number of<br /> + infralabials</td> + </tr> + <tr> + <td align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + </tr> + <tr> + <td align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9-10</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8-9</td> + </tr> + <tr> + <td align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + </tr> + <tr> + <td align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9-10</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 1</td> + <td style="border-width: 1px; border-bottom-style: solid; border-left-style: solid;" align="center"> 8-9</td> + <td style="border-width: 1px; border-bottom-style: solid; border-left-style: solid;" align="center"> 10</td> + </tr> + </tbody> + </table> +</div> +<p style="text-align: center"> </p> +<p style="text-align: center"> TABLE 4.—Analysis of Number of Scale Rows at Three Parts of the Body<br /> + in 81 Cottonmouths.</p> +<div class="c7"> + <table summary="analysis" cellpadding="2" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" rowspan="2" align="center"> Number<br /> + of scales<br /> + per row</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" colspan="2" align="center"> Neck</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" colspan="2" align="center"> Mid-body</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" colspan="2" align="center">Anterior to anus</td> + </tr> + <tr> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Number of<br /> + individuals</td> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Percentage</td> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Number of<br /> + individuals</td> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Percentage</td> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Number of<br /> + individuals</td> + <td style="border-left-style: solid; border-left-width: 1px; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px;" align="center">Percentage</td> + </tr> + <tr> + <td align="center"> 29</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 28</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3.7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 27</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 52</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 64.2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 26</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 16</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 18.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 25</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9.9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 67</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 82.7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 24</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4.9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> 23</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9.9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4.9</td> + </tr> + <tr> + <td align="center"> 22</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4.9</td> + </tr> + <tr> + <td align="center"> 21</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 68</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 84.0</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 6.2</td> + </tr> + </tbody> + </table> +</div> +<p>The number of scale rows on the neck, at mid-body, and just anterior + to the anus is relatively constant at 27-25-21, respectively; but some individual + variation is evident (Table 4). Since the rows are diagonally arranged, it is + necessary in counting scales to proceed either anteriorly or posteriorly across + the back; or the row may be counted in either direction up to the center of the + back and then reversed on the other side of the snake. In order to count the + scale rows in a position where no scale reduction or addition was occurring + and to avoid as much error as possible, I counted from anterior to center and + back on the neck, in any direction at mid-body, and from posterior to center + and back near the anus. Because females generally are the larger in circumference + posteriorly, they could have more scale rows than males just anterior <span class="pagenum"><a name="Page_447" id="Page_447">[447]</a></span> to the anus. The few snakes having more than 21 scale rows in the posterior + region offer no conclusive evidence as to tendencies, but in both instances in + which this occurred the females outnumbered the males three to one. An + odd, rather than an even, number of scale rows occurs on most of the length + of the snakes examined, because there is a mid-dorsal row and scale rows tend + to be lost on both sides at about the same level. An example of scale reduction + of one snake was as follows:</p> +<div class="c7"> + <table summary="scales" style="border-collapse: collapse" +width="100%" cellpadding="0"> + <tr> + <td align="right" class="tdr"> 6 + 7 (13)</td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> 6 + 7 (96)</td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + </tr> + <tr> + <td align="right" class="tdr"> 27 —————</td> + <td align="right" class="tdr"> 25 —————</td> + <td align="right" class="tdr"> 24 —————</td> + <td align="right" class="tdr"> 23 —————</td> + <td align="right" class="tdr"> 22 —————</td> + </tr> + <tr> + <td align="right" class="tdr"> 5 + 6 (13)</td> + <td align="right" class="tdr"> 5 + 6 (90)</td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> 7 + 8 (111)</td> + <td align="right" class="tdr"> 7 + 8 (114)</td> + </tr> + <tr> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + </tr> + <tr> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> 6 + 7 (122)</td> + <td align="right" + class="tdr"> </td> + <td align="right" class="tdr"> + 7, -5 (125)</td> + </tr> + <tr> + <td align="right" class="tdr"> 23 —————</td> + <td align="right" class="tdr"> 22 —————</td> + <td align="right" class="tdr"> 23 —————</td> + <td align="right" class="tdr"> 21 —————</td> + <td align="right" class="tdr"> 22 —————</td> + </tr> + <tr> + <td align="right" class="tdr"> -6 (118)</td> + <td align="right" class="tdr"> + 6 (119)</td> + <td align="right" class="tdr"> 6 + 7 (121)</td> + <td align="right" + class="tdr"> + 6 (123)</td> + <td align="right" class="tdr"> </td> + </tr> + <tr> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + </tr> + <tr> + <td align="right" class="tdr"> -6 (126)</td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + </tr> + <tr> + <td align="right" class="tdr"> 22 —————</td> + <td align="right" class="tdr"> 21 (130).</td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + </tr> + <tr> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"> </td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + <td align="right" class="tdr"></td> + </tr> + </table> +</div> +<p>This scale reduction follows the method proposed by Dowling (1951b: 133) + in which the numbers on the mid-line represent the number of scale rows, + upper figures refer to the right side of the snake, and figures in parentheses indicate + the number of the ventral scale (counted from the anterior end of the + series), thus marking the position of the addition or reduction. Addition of + a row is shown by a plus sign and the number of the row, whereas reductions + are shown by a minus sign and the number of the row that is lost or by a + plus sign between the number of two rows that join. According to Dowling, + variation in number of dorsal scales characterizes the few genera and species + of snakes in which it has been studied. The time and difficulty involved in + ascertaining the number of scales explain why it has not been widely used in + classification.</p> +<div class="figcenter" style="width: 500px;"> <img src="images/i_447.jpg" alt="Fig. 2. Number of ventral scales in 48 female and 34 male A. p. leucostoma." height="387" width="500" /> <span class="caption">Fig. 2. Number of ventral scales in 48 female and 34 + male <i>A. p. leucostoma</i>. </span></div> +<blockquote> + <p>Ventral scales on 34 males averaged 134.4 (128 to 139), and on 48 females + 133.5 (128 to 137) (Fig. 2.). Barbour (1956:34) found an average of 135.3 + ventral scales on 64 males and 44 females, and Gloyd and Conant (<i>loc. cit.</i>) + found an average of 134 for both males and females. The average for the + eastern cottonmouth obtained by Gloyd and Conant, however, was 137 ventrals + in both sexes. Some of my counts were made before I knew of the standard + system of counting ventrals proposed by Dowling (1951a:97-99), in which <span class="pagenum"><a name="Page_448" id="Page_448">[448]</a></span> the first ventral plate is defined as the most anterior one bordered on both + sides by the first row of dorsals. Therefore, some inconsistencies may exist in + my counts. Where differences occur, Dowling's method probably will indicate + the presence of an additional scale, since it appears to begin farther anteriorly + on the average, than I began counting.</p> +</blockquote> +<div class="figcenter" style="width: 500px;"> <img src="images/i_448.jpg" alt="Fig. 3. Number of caudal scales in 44 female and 34 male A. p. leucostoma." height="402" width="500" /> <span class="caption">Fig. 3. Number of caudal scales in 44 female and 34 + male <i>A. p. leucostoma</i>.</span> </div> +<p style="text-align: center"> </p> +<p style="text-align: center"> TABLE 5.—Caudal Scale Combinations in 95 Cottonmouths. U = Undivided;<br /> + D = Divided.</p> +<div class="c7"> + <table summary="scales" cellpadding="3" cellspacing="0"> + <tbody> + <tr> + <td rowspan="2" + style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" + align="center" class="tdc"><p style="text-align: center">Number<br /> + of<br /> + samples</p></td> + <td colspan="17" + style="border-left-style: solid; border-left-width: 1px; border-top-style: double; border-top-width: 4px;" + align="center" class="tdc"> Number of scales</td> + </tr> + <tr> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc">U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc">U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc"> U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc">D</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc">U</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid; border-bottom-style: solid;" + align="center" class="tdc">D</td> + </tr> + <tr> + <td align="center" class="tdc"> 25</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">13-35</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">10-32</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 11</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">12-33</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">14-28</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">16-39</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1-9</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">3-24</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 3-37</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1-21</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-5</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-29</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">14-30</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1-8</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-7</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-8</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">2-10</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">18-23</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1-2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">6-11</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">6-9</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1-17</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-8</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">13-22</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 4-16</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1-4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">18-21</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">11</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">10</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 13</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">4</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">13</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 17</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">3</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc">7</td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px;" + align="center" class="tdc"> </td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 9</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 8</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 3</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">3</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc"> 2</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" + align="center" class="tdc">6</td> + </tr> + </tbody> + </table> +</div> +<p>Analysis of caudal scales revealed sexual dimorphism. In the six specimens + from Tennessee, Blanchard (1922:16) found the same thing. Caudals averaged + 45.4 (41 to 50) on 34 males and 42.6 (39 to 49) on 44 females (Fig. 3). + Barbour (<i>loc. cit.</i>) found an average of 45.7 (30 to 54) caudals in males and + 43 (17 to 56) in females. Caudal scale counts by Gloyd and Conant (<i>loc. + cit.</i>) averaged 44 (38 to 49) in males and 42 (37 to 48) in females of <i>leucostoma</i>; + in <i>piscivorus</i> they averaged 48 (42 to 53) in males and 44 (41 to 49) + in females. Another seldom-mentioned, unusual characteristic of the caudal <span class="pagenum"><a name="Page_449" id="Page_449">[449]</a></span> scales of copperheads and cottonmouths is that some are single (usually those + at the base of the tail) and others divided (Table 5). To my knowledge, all + other species have either single or divided scales the entire length of the tail. + See Klauber (1941:73) and Fox (1948:252) concerning correlation of few + scales with warm environment.</p> +<h3>Dentition</h3> +<p>Cottonmouths, like other pit-vipers, have their teeth reduced in number + and have enlarged, highly specialized fangs. Small teeth occur on the palatine + and the pterygoid in the upper jaw and on the dentary in the lower jaw. The + dentary bone bears 17 curved teeth that decrease in size posteriorly. The + palatine bears five small, strongly curved teeth, and the pterygoid bears 16 to + 18 strongly curved teeth decreasing in size posteriorly. The numbers of teeth + mentioned above in each instance refer to the number of sockets rather than + the actual number of teeth, because teeth are frequently shed, leaving some + of the sockets empty at any one time.</p> +<p>The maxillary bone has two sockets side by side which bear the poison + fangs, usually one at a time. During the period shortly before a fang is to be + shed, however, its replacement becomes attached in the alternate socket; and + both fangs may be functional for a short time. The old fang then becomes + weakened at its base, eventually breaks off, and is swallowed. At any one + time four or five replacement fangs in various stages of development are found + in the gum behind the functional fang. These replacement fangs, which are + arranged in alternate rows, gradually enlarge as they move forward in their + development and, in juveniles, are generally slightly longer than the fangs that + they replace.</p> +<p>In 1963 I examined the fangs of 14 cottonmouths at four- to seven-day intervals + for a period of six weeks. The fang-shedding cycle was found to be + highly irregular, with a double condition (on one or both sides) occurring one-third + of the time. Approximately the same proportion of double fangs was + found in preserved individuals. A replacement period of at least five days + was observed in one snake. One-half the cycle (from replacement on one side + to replacement on the other) varied from five to twenty days, indicating that + the cycles for each fang are independent of one another. Bogert (1943:324) + found that young rattlesnakes are born with functional fangs in the two inner + sockets. Nonsynchronous use of the sockets on opposite sides of the head in + rattlesnakes is a later development which results from accidents or other conditions + leading to a longer retention of the fang on one side than on the other + (Klauber, 1956:723). I found a double set of fangs in cottonmouths only + twice in the six-week period. A complete cycle was recorded in ten instances + in a period of 19 to 23 days and in two instances in 32 days. One cottonmouth + was examined periodically over a 34-day period by Allen and Swindell + (1948:12), but a complete fang-shedding cycle was not observed. Fitch + (1960:110) reported a 33-day cycle in copperheads; Klauber (1956:726) + estimated the normal active life of each fang of an adult rattlesnake to be + from six to ten weeks, but he made no observations to confirm his estimation.</p> +<p>Fangs measured from the tip of the notch of the basal lumen to the end of + the fang vary from about 1.3 per cent of the snout-vent length in juveniles to + about 1.0 per cent in large adults (Table 6). The fangs are longer than those + of copperheads (Fitch, 1960:111). Klauber's (1956:736) figures on fang-lengths + in all species of rattlesnakes are percentages of total length rather than + of the snout-vent length. The fangs of various species of rattlesnakes range + from nearly the same proportionate length as those of cottonmouths to some + much longer.</p> +<p>From patterns of bites of venomous snakes, Pope and Perkins (1944:333-335) + attempted to correlate number, size, and patterns of tooth marks with + size and generic identity of the snake responsible for the bite. Distance between + fangs is relatively constant for snakes of a particular size (Table 6) regardless + of genus, but the fangs of a cottonmouth are directed outward to + variable degrees, and puncture wounds could easily resemble those of a much + larger snake (Table 7). Also there is no direct relationship between size of <span class="pagenum"><a name="Page_450" id="Page_450">[450]</a></span> snake and toxicity or amount of venom injected. Consequently information of + this kind is of little or no value from a medical standpoint.</p> +<p style="text-align: center"> </p> +<p style="text-align: center"> TABLE 6.—Correlation of Relative Fang-length and Distance Between Fangs<br /> + at Base with Snout-vent Length of Cottonmouths.</p> +<div class="c7"> + <table style="border-collapse: collapse;" summary="fangs" + cellpadding="3" width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Snout-vent length<br /> + (millimeters) </td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"><p style="text-align: center">Number + in<br /> + sample</p></td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"><p style="text-align: center">Average<br /> + ratio of<br /> + fang-length<br /> + to<br /> + snout-vent<br /> + length<br /> + (percent)</p></td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"><p style="text-align: center">Number<br /> + in sample</p> + <p> </p></td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Average<br /> + ratio of<br /> + distance<br /> + between<br /> + fangs to<br /> + snout-vent<br /> + length<br /> + (percent)</td> + </tr> + <tr> + <td align="center">200-299</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.33</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.57</td> + </tr> + <tr> + <td align="center">300-399</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.30</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.48</td> + </tr> + <tr> + <td align="center">400-499</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 13</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.21</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.21</td> + </tr> + <tr> + <td align="center">500-599</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.22</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.19</td> + </tr> + <tr> + <td align="center">600-699</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.17</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2.10</td> + </tr> + <tr> + <td align="center">700-799</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.07</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1.65</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center">800-899</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 1.00</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 2.00</td> + </tr> + </tbody> + </table> +</div> +<p> </p> +<p style="text-align: center"> TABLE 7.—Contrast in Measurements Between the Base of the Fangs and<br /> + Between Fang Punctures of Nine Cottonmouths (in millimeters).</p> +<div class="c7"> + <table cellpadding="3" summary="contrast" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Distance between<br /> + base of fangs</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Distance between<br /> + fang punctures</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Snout-vent<br /> + length</td> + </tr> + <tr> + <td align="center"> 7.7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 13.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 400</td> + </tr> + <tr> + <td align="center"> 8.7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 14.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 575</td> + </tr> + <tr> + <td align="center"> 10.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 22.5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 526</td> + </tr> + <tr> + <td align="center"> 11.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 18.0-19.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 590</td> + </tr> + <tr> + <td align="center"> 12.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 18.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 793</td> + </tr> + <tr> + <td align="center"> 13.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 17.0, 20.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 558, 612</td> + </tr> + <tr> + <td align="center"> 15.5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 23.5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 800</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 16.0</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 24.0</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 800</td> + </tr> + </tbody> + </table> +</div> +<hr class="chap" /> +<h2>HABITAT AND LIMITING FACTORS</h2> +<p>Although usually associated with swamps and lowlands along river bottoms, + the cottonmouth lives in a variety of habitats ranging from salt marshes to cool, + clear streams and from sea level to an altitude of 2300 feet. Shaded, moist + areas either in or beside shallow waters are preferred, but cottonmouths occasionally + wander as far as a mile from water.</p> +<p>In the pine-oak forests of Nacogdoches County in eastern Texas cottonmouths + and copperheads are probably the most abundant species of snakes. + Specimens have been collected near Nacogdoches in ponds, swamps, clear and + fast-running streams with rock bottoms, and sluggish muddy streams. On the + Stephen F. Austin Experimental Forest numerous cottonmouths live in a + swamp until around mid-July, when it becomes dry. A small stream west of <span class="pagenum"><a name="Page_451" id="Page_451">[451]</a></span> the swamp seems to be used as a migration route to and from the swamp. + Slightly more than a mile downstream cottonmouths are common in a bottomland + area. The ground is always moist and no undergrowth occurs; a few + small clear springs produce shallow trickles that run into a swamp. Cottonmouths + can often be found here, lying in or beside the small trickles.</p> +<p>I have seen cottonmouths in various types of aquatic habitats in Brazoria + County. In most places in this area, cottonmouths are found in association + with one or more species of water-snakes (including <i>Natrix cyclopion</i>, <i>N. + erythrogaster</i>, <i>N. rhombifera</i>, and <i>N. confluens</i>), which greatly outnumber the + cottonmouth. Interspecific competition may be reduced somewhat by cottonmouths + sometimes feeding on water-snakes.</p> +<p>The numerous statements in the literature concerning the habitat of the + cottonmouth can be summarized most easily by the following short quotations:</p> +<blockquote> + <p><i>Agkistrodon piscivorus piscivorus</i>—"Marshes and lakes; ponds and streams + with wooded shores; low country near water; roadside ponds; drainage ditches; + coastal 'banks'; keys; some Gulf coast islands; mangrove swamps." (Wright + and Wright, 1957:919.)</p> + <p><i>Agkistrodon piscivorus leucostoma</i>—"Cypress, gum, river swamps; alluvial + swamps wooded or not wooded; water courses of the south such as rivers, + bayous, backwaters of small branches; hill streams in the north; ... + marshy places in prairies ... rice fields, bottomland pools; margins of + above habitats, pools, shallow lakes, swampy places, temporary flood lands. + ... In, under, or on fallen timber, in holes in banks, rocky bluffs, crayfish + burrows. In short it is very aquatic." (Wright and Wright, <i>op. cit.</i>:923.)</p> +</blockquote> +<p>Geographically cottonmouths differ somewhat in their ecological requirements, + but are basically much alike in most respects. The areas of greatest + abundance are those having 40 inches or more of annual rainfall. The northern + edge of the range has a mean temperature of approximately 38° F. in January + in Virginia and 30° F. in Missouri, although the lowest temperature reached + in these areas is more important as a limiting factor. The annual rainfall in + both Virginia and Missouri amounts to approximately 40 inches. Moisture, + as well as temperature, may play an important role in the northward distribution + of the species. The eastern cottonmouth seems to be less tolerant of low + temperatures than the western subspecies. Mean January temperatures equal + to those along the northern limits of the western cottonmouth's distribution + are reached in the vicinity of Connecticut, which is north of the geographic + range of the eastern subspecies.</p> +<p>The depths to which cottonmouths penetrate into their dens may have a + limiting influence upon the geographic range, especially in the northern extremes. + Bailey (1948:215) discussed the possibility that populations of snakes + may be significantly depressed because of winter kill of individuals that "hibernate" + at shallow depths. He speculated also that the short growing season + does not allow enough time for the essentials of existence to be carried out, + and the prolonged period of inactivity overtaxes the energy reserve of the + species.</p> +<p>Available food does not seem to be of much importance as a limiting factor, + for the cottonmouth is remarkably indiscriminate in its choice of prey, feeding + upon almost any vertebrate animal that happens to come within reach. Competition + for food, however, may play an important role.</p> +<p><span class="pagenum"><a name="Page_452" id="Page_452">[452]</a></span></p> +<hr class="chap" /> +<h2>REPRODUCTION</h2> +<h3>Courtship and Mating</h3> +<p>A review of available literature indicates no records of courtship of the + cottonmouth other than statements that breeding occurs in early spring. In + a close relative, the copperhead (see Fitch, 1960:159-160), mating occurs + almost any time in the season of activity but is mainly concentrated in the + few weeks after spring emergence, at about the time when females are ovulating. + Klauber (1956:692) concluded that along the southern border of the + United States rattlesnakes normally mate in spring soon after coming out of + their winter retreats; but farther north where broods are produced biennially, + the mating times may be more widely dispersed, and summer and fall matings + may even predominate.</p> +<p>The only record of copulation in the cottonmouth was reported by Allen + and Swindell (1948:11), who observed a pair copulating for three hours on + October 19, 1946, at the Ross Allen Reptile Institute. Davis (1936:267-268) + stated that courtship in cottonmouths is violent and prolonged but did not + note any nervous, jerky motions or nudging of the female along her back and + sides as had been observed in other genera of snakes. Carr (1936:90) saw + a male cottonmouth seize a female in his mouth and hold her, but no courtship + followed.</p> +<h3>Reproductive Cycles</h3> +<p>Many persons have assumed that gestation periods in snakes are the intervals + between mating and parturition, and that mating and ovulation occur at approximately + the same time. However, retention of spermatozoa and delayed + fertilization indicate that copulation is not a stimulus for ovulation.</p> +<p>A biennial reproductive cycle was found for the copperhead in Kansas + (Fitch, 1960:162), the prairie rattler in Wyoming (Rahn, 1942:239) and in + South Dakota (Klauber, 1956:688), the great basin rattler in Utah (Glissmeyer, + 1951:24), and the western diamondback rattler in northwestern Texas (Tinkle, + 1962:309). Klauber's (1956:687) belief that the reproductive cycle of rattlesnakes + varies with climate, being biennial in the north and annual in the + south, is supported by similar climatic variation in the reproductive cycle of + the European viper which was discussed by Volsøe (1944:18, 149).</p> +<p>If data for a large number of females were arranged as are those in Table 8, + they might reveal whether the breeding cycle is annual or biennial. The figures + presented in Table 8 are misleading if viewed separately because of the small + number of individuals included in some of the size classes.</p> +<p>The smallest reproductive female found measured 455 millimeters in snout-vent + length. Conant (1933:43) reported that a female raised in captivity + gave birth to two young at an age of two years and ten months. The size + classes represented by gravid females found by Barbour (1956:38) in Kentucky + indicate that breeding occurs at least by the third year.</p> +<p>The ovaries of female cottonmouths examined revealed ova in various stages + of development. In individuals less than 300 millimeters in snout-vent length + the ovaries are almost completely undeveloped; in immature individuals from + 300 to 450 millimeters in length the follicles are from one to two millimeters + in length; in post-post females follicles vary in size, the largest being about + seven millimeters. Reproductive females also contain follicles of various sizes. <span class="pagenum"><a name="Page_453" id="Page_453">[453]</a></span> One or two sets are less than three millimeters in length, and large ova that + soon are to be ovulated are present. Ovarian ova found in April ranged in + length from 23 to 35 millimeters. No embryonic development was observed + in most individuals until June or later.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 8.—Percentage of Gravid Females of <i>A. p. leucostoma</i> in + 50 Millimeter Size Classes.</p> +<div class="c7"> + <table cellpadding="2" summary="gravid females" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Snout-vent<br /> + length</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Number of<br /> + gravid females</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Total number<br /> + in size class</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Percentage<br /> + gravid</td> + </tr> + <tr> + <td align="center">450-499</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 14</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 21.4</td> + </tr> + <tr> + <td align="center">500-549</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 17</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 41.2</td> + </tr> + <tr> + <td align="center">550-599</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 17</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 47.1</td> + </tr> + <tr> + <td align="center">600-649</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 71.4</td> + </tr> + <tr> + <td align="center">650-699</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 9</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 22.2</td> + </tr> + <tr> + <td align="center">700-749</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 66.7</td> + </tr> + <tr> + <td align="center">750-799</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 100.0</td> + </tr> + <tr> + <td align="center">850-899</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 100.0</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> Totals</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 29</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 69</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 42.0</td> + </tr> + </tbody> + </table> +</div> +<p>Increase in length of testes appears to be correlated with length of the + individual rather than cyclic reproductive periods (Fig. 4).</p> +<div class="figcenter" style="width: 500px;"> <img src="images/i_453.jpg" alt="Fig. 4. Length of testes in cottonmouths of various sizes" height="315" width="500" /> <span class="caption">Fig. 4. Length of testes in cottonmouths of various sizes <br /> + (<span class="xlfont"> ·</span>—left; </span> <span class="lfont">°</span><span class="caption">—right ). The right testis is always longer than + the left. </span></div> +<p>The reproductive cycle in cottonmouths resembles that illustrated by Rahn + (<i>op. cit.</i>:237), in which the ovarian follicles of post-partum females begin to + enlarge in late summer and autumn, with ovulation occurring the following + spring. By means of retaining sperm successive broods possibly are produced + after only one mating. In captivity, at least, some females may not follow + this biennial cycle; Stanley Roth (M.S.), biology teacher in high school at + Lawrence, Kansas, had a female of <i>A. p. piscivorus</i>, from Florida, that produced + broods of 14 and 12 young in two consecutive years.</p> +<p><span class="pagenum"><a name="Page_454" id="Page_454">[454]</a></span></p> +<h3>Embryonic Development</h3> +<p>After ova are fertilized a three and one-half to four-month period of development + begins which varies somewhat depending on the temperature. In + almost every instance the ova in the right uterus outnumber those in the left. + Embryos usually assume the serpentine form in the latter part of June and + are coiled in a counterclockwise spiral with the head on the outside of the + coil. At this time the head is relatively large and birdlike in appearance with + conspicuous protruding eyes. Sex is easily noted because the hemipenes of + males are everted. By late July scales are well developed and the embryo is + more snakelike in appearance, but pigmentation is still absent. By mid-August + the color and pattern are well developed, the egg tooth is present, the snake + shows a considerable increase in size over that of the previous month, and + much of the yolk has been consumed. Some females that contain well developed + embryos also contain eggs that fail to develop. Sizes of ova vary + irrespective of size of female and stage of embryonic development. Lengths + of ova ranged from 22 to 51 millimeters in May to 35 to 49 millimeters in + July and August. A two-yolked egg was found in one female.</p> +<h3>Birth of Young</h3> +<p>Accounts in the literature of 15 litters of cottonmouths fix the time of + birth as August and September. Conant (1933:43) reported the birth of a + litter in mid-July by a female that had been raised in captivity, and one female + that I had kept in captivity for two months gave birth to a litter between + October 19 and October 25. The conditions of captivity undoubtedly affected + the time of birth in both instances.</p> +<p>Wharton (1960:125-126) reported the birth and behavior of a brood of + seven cottonmouths in Florida. I was given notes of a similar nature by + Richard S. Funk of Junction City, Kansas, on a brood of five cottonmouths. + The mother of the brood was caught in June, 1962, in Tarrant County, Texas, + by Richard E. Smith, and was 705 millimeters in snout-vent length. The first + young was found dead in an extended position a few inches from the fetal + membranes at 11:05 p.m. on August 22. The second young was born at + 11:07 p.m. The intervals between the successive births were three, seven, + and four minutes; and time until the sac was ruptured in each instance was + six, five, eight, and 11 minutes. The time interval between the rupture of the + sac and emergence of each individual was 41, 92, 154, and 34 minutes. The + mother's actions in giving birth to the last four young were essentially as + described by Wharton (<i>loc. cit.</i>), except that the intervals between successive + births did not increase. Within one minute after rupturing the sac and while + its head was protruding, each of the four living young opened its mouth + widely from three to seven times, then took its first breath. Breaths for the + first three hours were steady at three or four per minute but then decreased + to two or three per minute. Pulse rate for the four averaged 38 per minute + while at rest but increased to 44 per minute after voluntarily crawling.</p> +<h3>Number of Young per Litter</h3> +<p>Records of from one to 16 young per litter have been reported (Ditmars, + 1945:330; Clark, 1949:259), but the average is probably between six or seven. + Most accounts in the literature present information on number of ova or embryos <span class="pagenum"><a name="Page_455" id="Page_455">[455]</a></span> per female rather than the number of young. Size and age of the + mother (Table 9) influence the number of ova produced. Allen and Swindell + (1948:11) recorded three to 12 embryos in 31 cottonmouths varying in total + length from 26 to 44 inches. An average of 6.5 embryos per female was + found.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 9.—Number of Ova Produced by Fecund Cottonmouths.</p> +<div class="c7"> + <table cellpadding="2" summary="ova" cellspacing="0" width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Snout-vent length<br /> + in millimeters</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Number<br /> + in sample</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Number of ova,<br /> + average and extremes</td> + </tr> + <tr> + <td align="center"> 450-549</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4.1 (2 to 7)</td> + </tr> + <tr> + <td align="center"> 550-649</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4.9 (1 to 8)</td> + </tr> + <tr> + <td align="center"> 650-749</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6.3 (4 to 8)</td> + </tr> + <tr> + <td align="center"> 750-849</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 850-949</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 14</td> + </tr> + </tbody> + </table> +</div> +<p>Mortality at birth has been recorded for almost every litter born in captivity + (see Allen and Swindell, <i>loc. cit.</i>; Conant, 1933:43; Wharton, 1960:125). + A female that I kept in captivity gave birth to seven young. Three never + ruptured their sacs, and another died soon after leaving the sac. The effects + of captivity on females may result in higher rates of deformity and mortality + in young than is common in nature. Klauber (1956:699-700) estimated that + the defects brought about by conditions of captivity on rattlesnakes eliminate + about three young per litter.</p> +<h3>Population Composition</h3> +<p>No investigator has yet analyzed the composition of a population of cottonmouths + according to age, sex and snout-vent length. Barbour (1956:35) did + sort 167 snakes into size classes, but did not determine sex ratio, size at sexual + maturity, reproductive cycles, or snout-vent length. He recorded total lengths + from which snout-vent lengths cannot be computed because of differential + growth rates and different bodily proportions of the two sexes. I judge from + my findings that he included immature individuals in his three smallest size + classes (45.5 per cent of the population). I found at least 32.5 per cent immature + individuals (Fig. 5) in my material, but it was not a natural population.</p> +<p>The sex ratios of several small collections from natural populations varied, + and no conclusions could be drawn. Females comprised 53 per cent of the + specimens included in Fig. 5 and in a group of 48 embryos which represented + eight broods. That percentage may not be the percentage in a natural population + but is used in making assumptions because I lack better information.</p> +<h3>Reproductive Potential</h3> +<p>If data in Fig. 5 are representative of a natural population and if 61 per + cent of the females are sexually mature, the reproductive potential can be + estimated as follows: assuming a cohort of 1000 cottonmouths contains 530 + females, 61 per cent of the females (323 individuals) probably are adults. + If 42 per cent of these females produce 6.5 young per female in any season + (Tables 8 and 9), 136 females will produce 884 young. But if 50 per cent <span class="pagenum"><a name="Page_456" id="Page_456">[456]</a></span> of the adult females are reproductive (as would be assumed if reproduction + is biennial), 1050 young will be produced. Actually the number of young + required per year to sustain a population is unknown, because mortality rates + at any age are unknown.</p> +<div class="figcenter" style="width: 500px;"> <img src="images/i_456.jpg" alt="Fig. 5. Composition of a group of cottonmouths" height="433" width="500" /> <span class="caption">Fig. 5. Composition of a group of cottonmouths examined in this + study. Individuals less than 450 millimeters in snout-vent length + are considered as immature. Specimens from 200 to 249 millimeters + in length are included in the 200-millimeter class, <i>etc.</i></span> </div> +<hr class="chap" /> +<h2>GROWTH AND DEVELOPMENT</h2> +<h3>Size at Birth and Early Growth</h3> +<p>Size at birth depends on the health of the mother. According to Fitch + (1960:182), many litters of copperheads born in captivity are stunted. Seven + young cottonmouths (two males and five females) born in captivity were each + 185 millimeters in snout-vent length and 40 millimeters in tail length. Weights + of the three living young were 10.0, 10.1, and 11.1 grams. Another litter of + five young measured by Richard S. Funk were larger, and differences in the + proportions of the tail length and snout-vent length suggest the sexual dimorphism + found in larger individuals. However, sex of these young snakes + was not recorded. Snout-vent length and tail length in millimeters were 232, + 41; 243, 47; 229, 40; 240, 48; and 225, 40 in the order of their birth. These + snakes are considerably smaller than the nine young of <i>A. p. piscivorus</i> reported + by Wharton (1960:127) that averaged 338 millimeters total length and 28.7 + grams. The yolk of one young <i>piscivorus</i> was 11.7 per cent of the total weight. <span class="pagenum"><a name="Page_457" id="Page_457">[457]</a></span> Yolk is used up in about two weeks if its rate of utilization resembles that of + the copperhead as reported by Gloyd (1934:600).</p> +<p>Early rates of growth of three living young are shown in Table 10. On + the 56th day after birth, each was fed one minnow less than two inches long. + Between the 80th and 120th days three additional small minnows were fed + to each snake. Young cottonmouths increase nearly 50 millimeters in length + by the first spring if they inhabit warm areas and feed in autumn or winter.</p> +<p>Variation in size of newborn cottonmouths may be less in nature than in + captivity. Average size at birth can be determined accurately by the size of + young captured in early spring, at least in northern parts of the range where + winter feeding and growth do not occur at all or are negligible. Total lengths + of 19 juveniles thought by Barbour (1956:38) to be seven to eight months old + do not differ markedly from lengths of the five newly-born young measured by + Funk.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 10.—Rate of Growth of Three Young Cottonmouths.</p> +<div class="c7"> + <table cellpadding="2" summary="growth rate" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td rowspan="2" style="border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Age<br /> + in days</td> + <td colspan="3" style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Snout-vent length / tail length—weight in grams</td> + </tr> + <tr> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> Female No. 1</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> Female No. 2</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> Male</td> + </tr> + <tr> + <td align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 185/40—11.1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 185/40—10.1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 185/40—10.0</td> + </tr> + <tr> + <td align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 192/40— </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 190/40— </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 189/40— </td> + </tr> + <tr> + <td align="center"> 22</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 195/40—10.3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 200/41.5—10.6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 197/40— </td> + </tr> + <tr> + <td align="center"> 80</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 204/40—11.7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 203/42—10.4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 218/48—14.3</td> + </tr> + <tr> + <td align="center"> 88</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> ....</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 204/44— </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> ....</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center">143</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 215/40.5—13.3</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> ....</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 225/48—15.1</td> + </tr> + </tbody> + </table> +</div> +<h3>The Umbilical Scar</h3> +<p>The umbilical cord is broken at birth and the navel closes within a few + days; but the scar, involving from two to four ventral scales, remains throughout + life. Position of the scar was found by Edgren (1951:1) to be sexually + dimorphic in the eastern hog-nose snake (<i>Heterodon platyrhinos</i>), but nothing + has been published on this matter concerning the cottonmouth. Consequently, + I counted the scales of several individuals from the anal plate, and there was + no marked difference in the position of the scar in males and females; it varied + in position from the 10th to the 18th scale. When counted from the anterior + end, the scar ranged from ventral number 115 to 122 (average, 119) in 28 + females and from number 117 to 126 (average, 121) in 14 males. The difference + between male and female cottonmouths is not nearly so great as in <i>Heterodon</i>.</p> +<h3>Later Growth and Bodily Proportions</h3> +<p>The only records of growth increments in a natural population of cottonmouths + are those in Table 11. The period of growth is mostly the period of + activity, and differences are expected between northern and southern populations. + As size increases, determination of growth rate becomes more difficult + because age classes overlap in size. Growth of any individual depends not + only on climate and food but also on disease and parasitism and the innate <span class="pagenum"><a name="Page_458" id="Page_458">[458]</a></span> size potential. Stabler (1951:91) showed weight and length relationships in + two cottonmouths for a period of six and one-half years.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 11.—Growth Increments in Cottonmouths (Barbour, 1956:38-39).</p> +<div class="c7"> + <table cellpadding="2" summary="increments" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Number of<br /> + individuals</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Total length<br /> + in millimeters</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Estimated age<br /> + in months</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Estimated growth<br /> + from preceding year<br /> + in millimeters</td> + </tr> + <tr> + <td align="center"> 19</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 260-298</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7-8</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 25</td> + </tr> + <tr> + <td align="center"> 11</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 312-337</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 19-20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 45</td> + </tr> + <tr> + <td align="center"> 40</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 355-485</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 31-32</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 95±</td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" align="center"> 83</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 500-1000</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 43-44+</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> ?</td> + </tr> + </tbody> + </table> +</div> +<p>My study failed to reveal any secondary sexual difference in growth rate + and maximum size. Of the 306 cottonmouths measured by me, 16 males and + five females exceeded 700 millimeters in snout-vent length. Two males were + more than 850 millimeters long. One cottonmouth lived in captivity for 18 + years and 11 months (Perkins, 1955:262). The maximum total lengths were + reported by Conant (1958:186-187) to be 74 inches (1876 mm.) in <i>A. p. + piscivorus</i> and 54 inches (1370 mm.) in <i>A. p. leucostoma</i>.</p> +<div class="figcenter" style="width: 500px;"> <img src="images/i_458.jpg" alt="Fig. 6. Head length ( ? ) and head width ( ? )" height="328" width="500" /> <span class="caption">Fig. 6. Head length (<span class="lfont"> ° </span>) and head width ( <span class="xlfont"> · </span>) expressed as a percentage + of snout-vent length of living and preserved cottonmouths. Head length + was measured from the tip of the snout to the posterior end of the mandible. + Head width was measured across the supraocular scales, since accuracy was + greater than if measured at the posterior edge of the jaw. No sexual dimorphism + or geographical variation occurs in these characters.</span> </div> +<p>Proportions of various parts of the body vary considerably depending on + age, size and, in some instances, sex. Heads are proportionately larger in + young than in adults (Fig. 6), as is true of vertebrates in general. This + larger head has survival value for the cottonmouth in permitting more venom <span class="pagenum"><a name="Page_459" id="Page_459">[459]</a></span> to be produced and in permitting it to be injected deeper than would be the + + case if the proportions were the same as in adults. Relative to the remainder + of the snake the head is considerably larger than in the copperhead (Fitch, + 1960:108) and slightly larger than in the rattlesnake, <i>Crotalus ruber</i> (Klauber, + 1956:152).</p> +<div class="figcenter" style="width: 500px;"><img src="images/i_459.jpg" alt="Fig. 7. Tail length expressed as a percentage of snout-vent length" height="275" width="500" /> <span class="caption">Fig. 7. Tail length expressed as a percentage of snout-vent length of living and preserved cottonmouths ( <span class="xlfont">·</span>—males; <span class="lfont">°</span>—females ). </span> </div> +<p>In general, tails are relatively longer in males than in females of the same + size (Fig. 7), except that there is little or no difference at birth. Growth of + the tail in males proceeds at a more rapid rate. In certain individuals sex + cannot be recognized from length of the tail relative to snout-vent length because + overlapping occurs, especially in medium-sized individuals. Similar + changes of proportions with increase in age occur in copperheads (Fitch, 1960:106) + and rattlesnakes (Klauber, 1956:158-159), but the tail of the cottonmouth + is relatively much longer.</p> +<hr class="chap" /> +<h2>SHEDDING</h2> +<h3>The Shedding Operation</h3> +<p>Shedding of the skin is necessary to provide for growth and wear in snakes. + The milkiness or bluing of the eyes, which causes partial blindness, marks the + initial stage of shedding and is caused by a discharge of the exuvial glands that + loosens the old <i>stratum corneum</i> from the layer below. In four to seven days + the opaqueness disappears, and the snake sheds after an additional three to six + days (Table 12). Young snakes first shed within a few days after birth and + generally shed more frequently than adults, but the interval is variable. The + eyes of three young cottonmouths observed by Wharton (1960:126) became + milky on the fourth day but cleared on the seventh day, and the skin was + shed on the eighth day. The eyes of three young kept by me became milky + two to three days after birth, cleared on the seventh to tenth days, and the + skin was shed on the thirteenth day. Possibly the relatively long interval in <span class="pagenum"><a name="Page_460" id="Page_460">[460]</a></span> this instance resulted from low relative humidity in the room where the + snakes were kept. According to Fitch (1960:134), litters of young copperheads + usually shed within three to ten days after birth; but under unusually + dry conditions shedding did not occur for several weeks.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 12.—Duration of Preparatory Period (in days) to Shedding in 11 + Cottonmouths.</p> +<div class="c7"> + <table cellpadding="2" summary="duration" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px; border-bottom-style: solid; border-bottom-width: 1px;" align="center"> Duration of<br /> + cloudiness<br /> + of eyes</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Time between<br /> + clearing and<br /> + shedding</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double; border-bottom-style: solid;" align="center"> Time from beginning<br /> + of cloudiness<br /> + until shedding</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + </tr> + <tr> + <td align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> -</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> -</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + </tr> + <tr> + <td align="center"> -</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> -</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + </tr> + <tr> + <td align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11</td> + </tr> + <tr> + <td align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 8</td> + </tr> + <tr> + <td align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> -</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> -</td> + </tr> + <tr> + <td align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + </tr> + <tr> + <td style="border-width: 1px; border-top: 1px solid rgb(0, 0, 0); border-bottom-style: solid;" align="center"><span style="text-decoration: overline">X</span> 5.4 </td> + <td style="border-width: 1px; border-top: 1px solid rgb(0, 0, 0); border-left-style: solid; border-bottom-style: solid;" align="center"><span style="text-decoration: overline">X</span> 3.8 </td> + <td style="border-width: 1px; border-top: 1px solid rgb(0, 0, 0); border-left-style: solid; border-bottom-style: solid;" align="center"><span style="text-decoration: overline">X</span> 9.0 </td> + </tr> + </tbody> + </table> +</div> +<p>Cottonmouths as well as other snakes usually do not feed until after the + skin is shed and are generally quiescent during the period preceding shedding, + except that immediately before shedding they become active and rub their + snouts on some rough object and may yawn several times seemingly in an + attempt to loosen the skin along the edges of the lips. After the skin is + loosened from the head, more rubbing against rough surfaces and writhing + serves to pull the old skin off, turning it inside out. Once the old skin has + passed over the thick mid-body, the snake often crawls forward using rectilinear + locomotion until the skin is completely shed. It normally comes off in + one piece; but, if the snake is unhealthy or has not had sufficient food or + water, the skin may come off in patches. Frequently one or both of the + lens coverings are not shed immediately and impair the sight. Bathing or + swimming ordinarily causes dried skin to peel off; and, because of the cottonmouth's + aquatic habits, its chances of shedding successfully are much greater + than those of less aquatic snakes. Cottonmouths that have recently shed + have bright and glossy patterns, in contrast to the dull and dark appearance + of those that are preparing to shed.</p> +<h3>Frequency of Shedding</h3> +<p>Most of our knowledge concerning the frequency of shedding is based + upon observations of captives. It is known that the intervals between exuviations + are largely dependent upon the amount of food taken and the rate of + growth. Unless laboratory conditions closely resemble those in the field, + shedding frequencies in captives probably differ much from those of free-living + snakes.</p> +<p>Only two of my captives shed twice. The intervals between exuviations <span class="pagenum"><a name="Page_461" id="Page_461">[461]</a></span> in the two snakes were eight and five months, lasting from August to April + and from December to May, respectively. Ten other snakes shed once in + the period from January through July. Stabler (1951:91) presented data + concerning shedding of two cottonmouths kept 12 and 14 years in captivity. + One shed 25 times in 12 years and the other shed 37 times in 14 years, giving + an average of 2.1 and 2.6 per year, respectively. Neither of the snakes + shed from December through March, but the period of shedding corresponded + to the period of greatest activity and growth. In Florida, cottonmouths shed + four to six times a year, according to rate of growth (Allen and Swindell, + 1948:7).</p> +<hr class="chap" /> +<h2>FOOD HABITS</h2> +<h3>Methods of Obtaining Prey</h3> +<p>Food is obtained by a variety of methods depending on the type of food, + age of the cottonmouth, and possibly other factors. Some captives lie in + ambush and others crawl slowly in active search. At the first cue of possible + prey, either by sight, scent, or differential temperature detection by the pit, + the snake appears to become alert and flicks its tongue out at fairly rapid + intervals.</p> +<p>By means of the facial or loreal pit found in all crotalids, the snake is able + to detect objects having temperatures different from that of the surroundings + of the objects. In detecting prey the tongue acts to sharpen the sense of + "smell" by conveying particles to Jacobson's organs in the roof of the mouth. + On many occasions cottonmouths appeared to rely solely on sight; they + passed within a few inches of prey, apparently unaware of its presence until + it moved. When pools of water begin to dry up toward the end of summer, + cottonmouths often congregate and feed on dying fish. In these instances + the fish are usually taken as they come to the surface. In laboratory observations + moccasins seize live fish and some moccasins carry the fish until they + have received lethal doses of venom; afterward the fish are swallowed. But + grasping and manipulation of the prey occurs without the fangs' being employed, + especially in the case of dead fish. On one occasion a cottonmouth + was observed to grasp the edge of a glass dish that had contained fish and + apparently retained the odor. On another occasion I placed several fish in a + bowl, rubbed a stick on the fish, and then touched each snake lightly on the + nose with the stick. The snakes crawled directly to the bowl and began + feeding. At other times these same snakes crawled around the cage in an + apparent attempt to locate the food but paid little attention to fish held in + front of them. If the catching of prey under natural conditions were as + uncoordinated as it sometimes is in captivity, the snakes probably would not + be able to survive.</p> +<p>Wharton (1960:127-129) described tail-luring in one individual of a 76-day-old + brood of cottonmouths. The snake lay loosely coiled with the tail + held about six centimeters from the ground; a constant waving motion passed + posteriorly through the terminal inch of the tail. These movements ceased + at 7:20 p.m. but were resumed at 7:40 a.m. the following day. All observations + were under artificial light. The "caudal lure" as a means of obtaining + prey has been described in other species and related genera by Neill (1960:194) + and Ditmars (1915:424).</p> +<p>Various authors have suggested that the method of capture differs according + to the kind of prey. Allen and Swindell (1948:5) stated that cottonmouths + retain their hold after striking fish or frogs but will release a mouse after + delivering a bite and are timid in striking at larger rodents. Neill (1947:203) + noted that a cottonmouth always waited several minutes after biting a large + rat before approaching its prey. This same type of behavior has been reported + for copperheads (Fitch, 1960:194) and rattlesnakes (Klauber, 1956:618). <span class="pagenum"><a name="Page_462" id="Page_462">[462]</a></span> Cottonmouths observed by me retained a strong hold on fish, frogs, and + sometimes mice, but almost always released large mice and baby chicks, + which were not eaten until after death.</p> +<p>Different behavior according to type of prey is correlated with ability of + prey to retaliate, although some animals may not be released because they + could easily escape. For instance, a frog could hop far enough to escape in + a matter of seconds if released. A 73-millimeter <i>Rana pipiens</i> that I observed + was bitten twice within one and a quarter hours and died 45 minutes after + the last bite. Its movement was uncoordinated by the time of the second bite, + but it could have escaped had the frog not been confined. Although it is + doubtful that normal, healthy fish are frequently captured by cottonmouths, + Allen (1932:17) reported that a cottonmouth was seen pushing a small, + dead pike about on the surface of a stream. A wound on the belly of the + fish indicated that it had been bitten. A 17-gram creek chub (<i>Semotilus</i>) + and a 13.7-gram bass (<i>Micropterus</i>) were injected by me with one-fourth + cubic centimeter of fresh venom near the base of the tail in order to determine + whether the fish could escape after being bitten and released. The creek + chub flipped onto its back after a minute and 45 seconds and gill movements + stopped in eight minutes and 35 seconds; the bass flipped over after 50 seconds + and died in two minutes and 10 seconds. The venom immediately affected + both fish, and it is unlikely that either could have swum more than a few feet.</p> +<p>After its prey has been killed, a cottonmouth examines the body from end + to end by touching it with the tongue. Then the animal is grasped in the + mouth without the use of the fangs and is slowly manipulated until one end + (usually the head) is held in the mouth. The lengthy process of swallowing + then takes place, the fangs and lower jaws alternately pushing the prey down + the throat.</p> +<h3>Food and Food Preferences</h3> +<p>The cottonmouth seems to be an opportunistic omni-carnivore, because it + eats almost any type of flesh that is available, including carrion. It feeds + primarily upon vertebrates found in or near water; but invertebrates and + eggs have also been found in the diet. The only potential prey items that + seem not to be normally eaten are bufonid toads and tadpoles. I have + occasionally offered tadpoles and frogs to cottonmouths, but only the frogs + were accepted. But, Stanley Roth kept a cottonmouth in captivity that ate + both toads and tadpoles. If tadpoles are commonly eaten, their probable + rapid digestion would make identification almost impossible.</p> +<p>Following is a list of known foods of the cottonmouth:</p> +<blockquote> + <p>Captivity: "... rattlesnake.... The same moccasin also killed + and ate a smaller snake of its own species...." (Conant, 1934:382.)</p> + <p>Florida: "3 heron feathers, bird bone, <i>Eumeces inexpectatus</i>, 3 fish all under + one inch in length, 1 heron egg shell" (Carr, 1936:89). According to Allen + and Swindell (1948:5), "the food included other moccasins, prairie rattlesnakes, + king-snakes, black snakes, water snakes, garter snakes, ribbon snakes, + and horn snakes ... most of the species of frogs, baby alligators, mice, + rats, guinea pigs, young rabbits, birds, bats, squirrels, and lizards ... + a mud turtle ... a case of a four footer eating ten to twelve chicken + eggs. The most common food appears to be fish and frogs. Catfish are + included on this list...." Yerger (1953:115) mentions "an adult yellow + bullhead, <i>Ameiurus natalis</i> ... 306 mm. in standard length [from a 63-inch + cottonmouth]."</p> +</blockquote> +<p><span class="pagenum"><a name="Page_463" id="Page_463">[463]</a></span></p> +<blockquote> + <p>Georgia: "... full grown <i>Rana catesbeiana</i>, several foot-long pickerel + ... dead fish if placed in a pan of water.... <i>Natrix sipedon + fasciata</i> and <i>Masticophis flagellum</i> ... rats.... Toads and large <i>Eumeces laticeps</i> were always ignored." (Neill, 1947:203.) "<i>Natrix</i>, <i>Heterodon</i>, <i>Kinosternon</i>, <i>Rana</i>, <i>Hyla cinerea</i>, <i>Microhyla</i>, Microtine [<i>Pitymys pinetorum</i>]." + (Hamilton and Pollack, 1955:3.)</p> + <p>Mississippi: "... <i>Hyla gratiosa</i>.... In captivity specimens have + eaten frogs, mice, birds, dead fish, pigmy rattlers and copperheads. Toads + ... were refused" (Allen, 1932:17). One moccasin "disgorged a smaller + decapitated moccasin ... killed the day before by boys" (Smith and + List, 1955:123).</p> + <p>Tennessee: "Beetles in one stomach; lizard (<i>Eumeces</i>) in another stomach; + small snake (<i>Natrix</i>) in one intestine, and hair in another intestine. One + stomach contained numerous bits of wood, up to four inches in length...." + (Goodman, 1958:149.)</p> + <p>Kentucky: "<i>Siren intermedia</i> was the most abundant food item in both + volume and occurrence. Frogs of the genus <i>Rana</i> ranked second. Together, + these two items comprised almost <span class="top">2</span>/<span + class="bottom">3</span> of the food of the snakes. The other + food items were distributed among the fishes, reptiles, and other amphibians + [one <i>Rana</i> tadpole included]." (Based on 42 samples—Barbour, 1956:37.)</p> + <p>Illinois: (Based on 84 samples—Klimstra, 1959:5.)</p> + <div class="c7"> + <table cellpadding="2" summary="food" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td align="left"><i>Food Item</i></td> + <td align="center"><i>Per cent Frequency<br /> + of Occurrence</i></td> + <td align="center"><i>Per cent<br /> + Volume</i></td> + </tr> + <tr> + <td align="left">Pisces</td> + <td align="center">39.3</td> + <td align="center">31.9</td> + </tr> + <tr> + <td align="left">Amphibia</td> + <td align="center">36.9</td> + <td align="center">26.0</td> + </tr> + <tr> + <td align="left">Reptilia</td> + <td align="center">25.0</td> + <td align="center">18.2</td> + </tr> + <tr> + <td align="left">Mammalia</td> + <td align="center">30.9</td> + <td align="center">17.9</td> + </tr> + <tr> + <td align="left">Gastropoda</td> + <td align="center">17.8</td> + <td align="center">1.0</td> + </tr> + <tr> + <td align="left">Miscellaneous</td> + <td align="center">25.0</td> + <td align="center">5.0</td> + </tr> + <tr> + <td align="center">(Algae, Arachnida, Aves, Insecta)</td> + <td colspan="2" align="left"> </td> + </tr> + </tbody> + </table> + </div> + <p>Louisiana: Penn (1943:59) mentions that a "female had just eaten two + young cottonmouths...." Clark (1949:259) mentions "100 specimens—34 + fish; 25 <i>Rana pipiens</i>; 16 <i>Rana clamitans</i>; 7 <i>Acris</i>; 4 <i>Natrix sipedon confluens</i>; + 8 birds; 5 squirrels ... catfish thirteen and one-half inches in length + ... small-mouth black bass [eleven inches]."</p> + <p>Oklahoma: Force (1930:37) remarks that the moccasin "eats bullfrogs + ... but refuses leopard frogs." Trowbridge (1937:299) writes: "several + sun perch.... Another had eaten six catfish six to ten inches long + ... a water snake (<i>Natrix s. transversa</i>) about 18 inches long ... + frogs, mostly <i>Rana sphenocephala</i>." Carpenter (1958:115) mentions "a + juvenile woodthrush.... Seven last instar cicadas ... a young + cottontail." According to Laughlin (1959:84), one moccasin "contained the + following items: 18 contour feathers of a duck, probably a teal; one juvenile + cooter turtle, <i>Pseudemys floridana</i>; and a large mass of odd-looking unidentifiable + material. The other cottonmouth contained one juvenile pond turtle, <i>Pseudemys scripta</i>...."</p> + <p>Texas: "... several ... feeding on frogs.... One ... + found DOR was found to contain a large catfish." (Guidry, 1953:54.)</p> +</blockquote> +<p>Of 246 cottonmouths that I examined for food items, only 46 contained + prey in their digestive tracts. Almost all of the snakes examined were + museum specimens that had been collected at many places over a period + of about 40 years. It was not known how long each had been kept alive + before being preserved. Therefore it was impossible to determine what + proportion of any population of cottonmouths could be expected to contain + food. The food items were not analyzed numerically because the scales and + hair, by means of which many food items in the intestine were identified, + yielded no clue as to the number of individuals actually present unless several <span class="pagenum"><a name="Page_464" id="Page_464">[464]</a></span> distinct kinds were found. Each occurrence of scales or hair was thus recorded + as a single individual, although some such occurrences may have represented + more than one animal. The contents of some stomachs were so well digested + that it was difficult to determine the number of items present. As a rule + only one food item was present in a digestive tract, but a few tracts contained + several items of the same or different species. Three frogs (<i>Acris crepitans</i>) + were in one snake and three hylas (<i>Hyla versicolor</i>) in another. Still another + individual captured beside a drying pond contained six individuals of <i>Lepomis</i> each about three inches long and two pikes (<i>Esox</i>) about six inches long.</p> +<p style="text-align: center"> </p> +<p style="text-align: center">TABLE 13.—Analysis of Food Items of 46 Cottonmouths Collected in + Arkansas, Louisiana, and Texas (1922-1962).</p> +<div class="c7"> + <table cellpadding="2" summary="food items" cellspacing="0" + width="80%"> + <tbody> + <tr> + <td style="border-top-style: double; border-top-width: 4px;" align="center"> </td> + <td style="border-top-style: double; border-top-width: 4px;" align="center"><span class="smcap"> Food Items</span></td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double;" align="center"> Number of<br /> + samples in<br /> + which item<br /> + occurred</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double;" align="center"> Percent<br /> + frequency<br /> + of<br /> + occurrence</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double;" align="center"> Estimated<br /> + weight<br /> + in<br /> + grams</td> + <td style="border-left-style: solid; border-width: 4px 1px 1px; border-top-style: double;" align="center"> Estimated<br /> + percentage<br /> + by<br /> + bulk</td> + </tr> + <tr> + <td style="border-width: 1px; border-top-style: solid;" colspan="2" align="left">Fish</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> (7)</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 13.2</td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-top-style: solid;" align="center"> 18.4</td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Esox</i> sp.</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Lepomis</i> sp.</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 15</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Unidentified</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td colspan="2" align="left">Amphibians</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> (12)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 23.0</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20.4</td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Scaphiopus hurteri</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 13</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Acris crepitans</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td> </td> + <td align="left"><i>Hyla cinerea</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Hyla versicolor</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Rana catesbeiana</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Rana pipiens</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 15</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Unidentified</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td colspan="2" align="left">Reptiles</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> (15)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 28.4</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 29.9</td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Pseudemys scripta</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 15</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Anolis carolinensis</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Eumeces fasciatus</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Lygosoma laterale</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Natrix</i> sp.</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Natrix erythrogaster</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 10</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Agkistrodon piscivorus</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Crotalus</i> sp.</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 30</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Unidentified snakes</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td colspan="2" align="left">Birds</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> (4)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 7.6</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 18.6</td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Anhinga anhinga</i> (juv.)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 60</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Egret (head and neck)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Passeriformes</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 2</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 20</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td colspan="2" align="left">Mammals</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> (6)</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 11.3</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12.7</td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"><i>Blarina brevicauda</i></td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 1</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 12</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="center"> </td> + <td align="left"> Cricetinae</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 5</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> 18</td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td align="left"> </td> + <td align="left"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px;" align="center"> </td> + </tr> + <tr> + <td style="border-width: 1px; border-bottom-style: solid;" colspan="2" align="left">Unidentified</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> (9)</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> 17.0</td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + <td style="border-left-style: solid; border-width: 1px; border-bottom-style: solid;" align="center"> </td> + </tr> + </tbody> + </table> +</div> +<p>The "unidentified" category (Table 13) refers to jellylike masses in the + stomach or material in the intestine in which no scales, feathers, hair, or bones <span class="pagenum"><a name="Page_465" id="Page_465">[465]</a></span> could be found. Most of the unidentifiable matter could be assumed to + consist of remains of amphibians, since they leave no hard parts. If this + assumption is correct, amphibians comprise about 40 per cent of the diet. + Since intestinal contents were included, a volumetric analysis was not feasible. + Therefore, the weight of each type of food item was estimated and the + percentage by bulk calculated from it (Table 13).</p> +<p>Pieces of dead leaves and small sticks constituted most of the plant material + found and presumably were ingested secondarily because they adhered to the + moist skin of the prey, especially to fish and amphibians. However, some + plant materials probably are eaten because they have acquired the odor of + the prey. One cottonmouth contained a <i>Hyla cinerea</i>, several leaves, and five + sticks from 37 to 95 millimeters long and from 12 to 14 millimeters in diameter.</p> +<p>Most reports in the literature state that gravid females do not feed, but + four gravid females examined by me containing large, well-developed embryos + also contained evidences of having recently fed. Two of them had scales of + snakes in the stomach or intestine, one contained a six-inch <i>Lepomis</i>, and the + other had hair in the intestine and the head and neck of an adult egret in the + stomach.</p> +<hr class="chap" /> +<h2>MORTALITY FACTORS</h2> +<h3>Natural Enemies and Predators</h3> +<p>Published records of other animals preying on cottonmouths or killing them + are few. Reptiles more often than other classes of vertebrates prey on the + cottonmouth. McIlhenny (1935:44) reported on the scarcity of snakes in + areas where alligators were present. Predation on cottonmouths by indigo + snakes (<i>Drymarchon corais</i>) was reported by Conant (1958:153) and Lee + (1964:32). Allen and Swindell (1948:6) obtained a photograph of a king-snake + (<i>Lampropeltis getulus</i>) killing a cottonmouth but thought that moccasins + are not eaten by <i>L. getulus</i>. However, one occasion reported herein shows that + cottonmouths are eaten by king-snakes; and Clark (1949:252) reported finding + 13 cottonmouths, along with other prey, in the stomach contents of 301 king-snakes + (<i>L. g. holbrooki</i>) from northwestern Louisiana. Cannibalism is also + common among cottonmouths. Klauber (1956:1058;1079) cited predation + on cottonmouths by a blue heron (<i>Ardea herodias</i>) and a largemouth bass + (<i>Micropterus salmoides</i>). Man is probably the greatest enemy of the cottonmouth. + Intentional killing, capturing, road kills, and alteration of the environment + destroy large numbers.</p> +<h3>Parasites and Diseases</h3> +<p>Allen and Swindell (1948:12) listed several diseases and parasites of snakes + and stated that "some moccasins captured in the woods are so poor and weak + from parasitic infection that they can barely crawl." The only kind of ectoparasite + found on captive cottonmouths in the course of my study was a snake + mite, <i>Ophionyssus natricus</i>. An infestation of that mite was thought to be + partly responsible for the death of one captive moccasin. Other moccasins + spent increasing amounts of time in their water dish after they became + infected with mites. Under natural conditions frequent swimming probably + keeps cottonmouths nearly free of mites.</p> +<p>Endoparasites found included lung flukes, stomach nematodes, and tapeworms. + Lung flukes (<i>Ochetosoma</i> sp.) were found in 16 of 20 captive cottonmouths. <span class="pagenum"><a name="Page_466" id="Page_466">[466]</a></span> Snails and frogs serve as intermediate hosts for various stages in + the life cycle of these flukes. The high percentage of cottonmouths infested + with flukes is indicative of the use of frogs as a major source of food. Less + than ten flukes were usually observed in the snakes' mouths but occasionally + more were seen. One snake was observed thrashing about in its cage for + nearly an hour, after which time it died. Upon examination of the mouth, + 32 flukes were found, most of which were located in the Jacobson's organs. + Whether or not flukes caused the death is not known. Nematodes (<i>Kalicephalus</i> sp.) were found in the stomach of each of several preserved specimens; + most of these snakes had no food in their digestive tracts. In a high percentage + of the moccasins, tapeworms (<i>Ophiotaenia</i> sp.) were in the duodenum, + in many instances so tightly packed as seemingly to prevent passage of food. + The importance of fish in the diet is reflected by the high percentage of + snakes containing tapeworms. An unidentified cyst (?) about an inch long + and containing two hooks on one end was found attached to the outer wall + of the stomach of a cottonmouth. Yamaguti (1958) listed all the kinds + of helminths known from cottonmouths.</p> +<h3>Miscellaneous Causes of Death</h3> +<p>Munro (1949:71-72) reported on the lethal effect of 10 per cent DDT + powder on two young cottonmouths which were dusted with it to kill mites. + Herald (1949:117) reported an equal effect caused by spraying a five per cent + DDT solution in a room with several snakes. All but three large cottonmouths, + which were under shelter at the time of spraying, were killed.</p> +<p>One individual that refused to eat was dissected soon after death, and a + short piece of a branch on which two large thorns were located at 90° angles + was found blocking the intestine at the posterior end of the stomach.</p> +<p>An unexpected and probably unusual circumstance caused the death of two + captives. After cleaning a cage containing five cottonmouths and placing + several mice in the cage for food, I noticed two of the snakes lying stretched + out, partially on one side, and almost unable to move. At first I thought they + had been bitten by other snakes which were in pursuit of the mice. The two + died after two days. When a similar incident occurred in another cage, I + removed the "bitten" snake and it fully recovered after 11 days. When + the same symptoms were observed in a garter snake in another cage, I + realized that in each instance the cage had been cleaned and fresh cedar + chips placed in it immediately prior to observation of these symptoms. Fine + cedar dust on the chips had evidently poisoned the snakes.</p> +<hr class="chap" /> +<h2>BEHAVIOR</h2> +<h3>Annual and Diel Cycles of Activity</h3> +<p>In the days following emergence in spring, cottonmouths often endure uncomfortable + and even dangerous temperatures in order to obtain food and + mates. They are more sluggish at this time and more vulnerable to predation + than later in the season when temperatures are optimal. Fitch (1956:463) + found that copperheads in northeastern Kansas begin their annual cycle of + activity in the latter part of April, when the daily maximum temperature is + about 22° C. and the minimum is about 4° C., and become dormant in late <span class="pagenum"><a name="Page_467" id="Page_467">[467]</a></span> October or early November, at which time the daily maximum temperature is + about 15° and the minimum is about 0°. Indications are that in the northern + part of its range the annual activity cycle of the cottonmouth resembles that + of the copperhead in northeastern Kansas. Klimstra (1959:2) captured cottonmouths + from April to October in southern Illinois. Barbour (1956:36) collected + large numbers of them in early April in Kentucky and stated that they + migrate from swamps to wooded hillsides in late August and early September. + Spring migrations begin after a few consecutive warm days in March. In + northern Oklahoma cottonmouths have been found along the Verdigris River + as early as March, suggesting that a few winter in crayfish holes and mammal + burrows. The majority of individuals found in this area were at denning sites + along cliffs above the river and emerged later than those near the river (Dundee + and Burger, 1948:1-2). In Virginia cottonmouths have been seen as early as + March 5 (Martin and Wood, 1955:237) and as late as December 4. They + have been observed in migration from the swamps of the barrier beach to the + mainland in late October and early November in southeastern Virginia (Wood, + 1954a:159). According to Neill (1947:204), the cottonmouth tolerates lower + temperatures than do most snakes in Georgia and is one of the last to go into + hibernation. Allen and Swindell (1948:4) stated that cottonmouths usually + bask during the mornings of the cooler months in Florida, but they mentioned + nothing of denning such as occurs farther north. Although winter aggregations + occur in the northern parts of the range, I have never seen such aggregations + in the South. However, in one instance related to me by a reliable + observer, seven cottonmouths were found together on a creek bank near the + Gulf Coast in early spring.</p> +<p>During late summer and early autumn, fat is deposited in lobes in the lower + abdomen in preparation for the period of winter quiescence. Gravid females + usually do not feed so frequently or so much as other snakes, because they + tend to become inactive as the ova develop. Whether or not females feed + heavily after parturition and previous to denning is not known. Peaks of + activity in autumn may be caused by final attempts to feed before denning + and by the appearance of large numbers of newborn young. The young + usually have from one to two months in which to feed before the advent of + cold weather. According to Barbour's (<i>op. cit.</i>:38) findings, the young probably + feed before hibernation because they grow substantially in winter. For + those that do not feed, the rate of survival is perhaps much lower.</p> +<p>In preparation for winter, cottonmouths migrate inland, usually to dry + forested hillsides where they den, commonly among rocks at the tops of bluffs, + along with several other species of snakes. In such aggregations there is no + hostility and each individual may derive benefit from contact with others by + which favorable conditions of temperature and humidity are maintained.</p> +<p>Neill (1947:204) has found many specimens in winter by tearing bark from + rotting pine stumps on hillsides overlooking lakes or streams. On cold days + they evidently retreat below the surface, while on warm days they lie just + below the bark or emerge and bask. Neill believes that the use of stumps by + cottonmouths is an innate pattern of behavior, because of the large number + of young-of-the-year found in such surroundings. Cottonmouths were observed + in winter also under logs and stumps by Allen (1932:17). I have + twice observed cottonmouths crawling into crayfish burrows along the Gulf + Coast of Texas, and suppose they are used as denning sites to some extent.</p> +<p><span class="pagenum"><a name="Page_468" id="Page_468">[468]</a></span></p> +<p>The diel cycle of activity of cottonmouths is of necessity closely related + to the seasonal cycle. Since optimal temperatures determine activity, the + diel cycle varies greatly from time to time. It has been well established + that cottonmouths, like most other crotalids and many snakes of other families, + prefer nocturnal to diurnal activity, even though the temperature may be + less favorable at night. This preference is correlated with increased nocturnal + activity of frogs and reptiles that constitute the principal food supply.</p> +<p>During spring and autumn, activity is more restricted to the day and long + periods of basking occur. However, as hot weather approaches, basking + occurs mainly in the morning and evening and activity becomes primarily + nocturnal. But, in well shaded, moist forests, cottonmouths feed actively in + the daytime.</p> +<p>Availability of food also has an important influence upon activity. Allen and + Swindell (<i>op. cit.</i>:5) stated that moccasins congregate around drying ponds + and feed on dying fish until the moccasins can hold no more. They then + usually stay nearby as long as food remains. In an area of the Stephen F. + Austin Experimental Forest near Nacogdoches, Texas, many cottonmouths + journey daily to and from a swamp and a dry field, evidently to feed on + rodents inhabiting the area. Ten individuals captured along a snake-proof + fence that was built 30 yards from the swamp were found lying coiled along + the fence after 4:30 p.m., at which time the area was shaded. On another + occasion, I captured a large cottonmouth that was feeding upon dying fish + in a drying pool about 10:30 a.m. on August 19, 1962.</p> +<p>Because of the aquatic habits of the cottonmouth, relative humidity probably + has little influence on the snake's activity. However, cottonmouths are + more restricted to the vicinity of water in dry weather than during rains or + muggy weather when many of their natural prey species also move about + more freely. Increased activity on cloudy days may result from protection + from long exposure to sunshine. Torrential rains and floods, such as those + following hurricanes along the Gulf and Atlantic coasts of the southeastern + United States, bring out quantities of snakes of all species. Rattlesnakes and + cottonmouths in particular are killed by the thousands at these times because + they seek shelter in human habitations. However, these are unusual circumstances + and do not reflect voluntary activity as a result of preferences.</p> +<p>Thermal reactions of reptiles were classified by Cowles and Bogert (1944) + into several categories. For each species there is a basking and normal + activity range limited by the voluntary minimum and voluntary maximum at + which the animal seeks shelter. Beyond this normal range are the critical + thermal minimum and critical thermal maximum (C. T. M.) at which effective + locomotion is prevented. The lethal minimum and maximum are those + temperatures at which short exposure produces irreparable damage, and death + inevitably results. These classifications are modified somewhat by seasonal + or laboratory acclimation or by the physiological state of the animal. The + C. T. M. of five cottonmouths was determined by placing each individual + in an enclosed area and heating it with an infrared lamp. Cloacal temperatures + were taken with a Schultheis quick-recording thermometer as soon as + the snake could no longer right itself when placed on its back. All temperatures + were in degrees Celcius. The C. T. M. averaged 39.2° (38.0° to 40.0°). A + temperature of 38.0° was lethal to one individual. These cottonmouths had <span class="pagenum"><a name="Page_469" id="Page_469">[469]</a></span> been in captivity for nine months. The behavior of the snakes during heating + resembled those instances described by Klauber (1956:382-387) for rattlesnakes. + As the body temperature of the snakes rose past the optimum, each + individual became disturbed and tried to escape from the enclosure. The + snakes soon became frantic in their efforts to escape. After about five minutes + the mouth was opened and heavy, slow breathing was begun, accompanied by + a loss of coordination and a slowing down of movements. The snakes writhed + spasmodically for a few seconds and then lay still, usually with the mouth + open. Recovery was begun by rolling on the belly and flicking the tongue, + followed by movements of the head and then the body. Cottonmouths are + rarely exposed to dangerously high temperatures owing to their semi-aquatic + habits, but there are probably occasions when individuals reach the C. T. M. + for the species.</p> +<h3>Basking</h3> +<p>Since activity, digestion, and gestation depend upon adequate internal + temperatures, there must be a process by which these temperatures are attained + and for an appropriate time maintained. Basking is important in this respect. + The cottonmouths prefer to lie in a coiled position and, during basking, can + usually be found beside bodies of water or on branches of dead trees overhanging + the water. They are good climbers and have a prehensile tail that is + frequently employed in descending from small branches. Since cottonmouths + are semi-aquatic and are often exposed to temperatures that are lower than + those of the air, they either must bask more often than terrestrial snakes + or tolerate lower temperatures. Length of the period of basking is determined + not only by amounts of insolation and temperature but also by the size of the + snake. A smaller snake can reach its optimum temperature more rapidly + because of a higher surface-to-volume ratio. Another factor that may play + a minor role in the rate of temperature change is the color of the snake. The + wide variation in color of cottonmouths probably affects rates of heat increase + and loss due to direct radiation. Slight hormonal control of melanophores + described in snakes by Neill and Allen (1955) also may exert some influence + on the length of time spent basking. No rates of temperature increase or + decrease are available for cottonmouths.</p> +<h3>Coiling</h3> +<p>While inactive the cottonmouth spends most of its time lying in a coiled + position with the tail outermost, with the body usually wound into about one + and one-half cycles, and the head and neck in a reversed direction forming a + U- or S-shaped loop. From this position the snake is able to make a short + strike or a hasty getaway if necessary. In my opinion this position is used + primarily for basking or resting and only secondarily for feeding. Most + individuals appear to pursue their prey actively, not lying in ambush for the + approaching prey to the extent that most other crotalids do.</p> +<p>Many of the cottonmouths that I kept in captivity were observed in a coiled + position for periods up to three or four days. Under natural conditions, however, + they are more active. Young cottonmouths are inclined to remain in a + coiled position for longer periods than older individuals.</p> +<p><span class="pagenum"><a name="Page_470" id="Page_470">[470]</a></span></p> +<h3>Locomotion</h3> +<p>Four distinct types of locomotion have been described in snakes: horizontal + undulatory, rectilinear, sidewinding, and concertina (Klauber, 1956: + 331-350). Most snakes are capable of employing two or more of these types + of progression, at least to a certain degree; but horizontal undulatory locomotion + is the most common method used by the majority of snakes, including + the cottonmouth. In this method the snake's body is thrown into lateral + undulations that conform with irregularities in the substrate. Pressure is + exerted on the outside and posterior surface of each curve, thus forcing the + body forward.</p> +<p>Rectilinear locomotion is more useful to large, thick-bodied snakes which + use this method of progression, chiefly when they are prowling and unhurried. + This method depends upon the movement of alternate sections of the venter + forward and drawing the body over the ventral scales resting on the substratum + by means of muscular action. This mode of locomotion was most + frequently observed in captive cottonmouths when they were crawling along + the edge of their cages, especially when they were first introduced to the cages + and toward the end of the shedding process. The other two types of locomotion, + sidewinding and concertina, have not, to my knowledge, been observed + in the cottonmouth.</p> +<p>Both the cottonmouth and the cantil have definite affinities for water and + are as likely to be found in water as out of it. Copperheads and rattlesnakes, + although not aquatic, are good swimmers. When swimming, a motion resembling + horizontal undulatory progression is used.</p> +<h3>Disposition</h3> +<p>The number of different opinions expressed in the literature concerning the + cottonmouth's disposition is not at all surprising. As with any species there is + a wide range of individual temperament, which is affected by many factors. + The cottonmouth is considered by some writers to be docile while others consider + it to be highly dangerous. Allen and Swindell (1948:7) described the + variability in temperament, even among individuals. They wrote: "On rare + occasions, moccasins are found which will attack. A perfectly docile snake + will turn and bite viciously without any apparent reason." They also recounted + a case in which a cottonmouth was kept as a pet for six years, being + allowed the freedom of the house. Smith and List (1955:123) found them + "... surprisingly docile in the gulf region [Mississippi], displaying none + of the pugnacity of more northern cottonmouths." Smith (1956:310) stated: + "Unlike the copperhead, cottonmouths are pugnacious; their powerful jaws, + long fangs, vicious disposition and potent venom make them a very dangerous + animal."</p> +<p>My own observations are in general agreement with the statements of Allen + and Swindell (<i>loc. cit.</i>). In my encounters with cottonmouths, I have never + found any aggressive individuals except for three juveniles that were born in + captivity. In their first three days in the laboratory these juveniles were observed + to strike repeatedly whenever anyone entered the room. After this short + period of aggressiveness, however, they slowly became more docile. The disposition + shown by the newborn young is clearly an innate behavioral pattern + that undoubtedly has a direct relationship to survival. The majority of cottonmouths <span class="pagenum"><a name="Page_471" id="Page_471">[471]</a></span> that I have approached in the field have moved swiftly to seek refuge + in nearby water; a few have remained motionless as I approached, and one + showed the typical threat display. Upon capture and handling, they react + similarly to other pit-vipers by opening and closing the mouth and erecting + the fangs in an attempt to bite. They often bite through the lower jaw and + eject venom at this time as well as when the mouth is open. Of more than a + dozen individuals kept in captivity, four were particularly difficult to handle + whereas another was extremely docile. It was almost never found in aggregations + with the other snakes and did not struggle or attempt to bite when + handled. The majority remained unpredictable in disposition, usually appearing + docile and lazy but capable of extremely rapid movements when disturbed.</p> +<h3>Defense and Escape</h3> +<p>The typical threatening posture of rattlesnakes is all but lacking in the + cottonmouth, which relies primarily on concealing coloration or nearness to + water for escape. When approached, it usually plunges into nearby water or + remains motionless with the head held up at a 45° angle and the mouth + opened widely exposing the white interior. The tail is sometimes vibrated + rapidly and musk is expelled. This threat display is unique to cottonmouths; + although it does not attract as much attention as the display of rattlesnakes, + it is probably an effective warning to most intruders at close range.</p> +<p>Neill (1947:205) reported one case in which a cottonmouth used the "body + blow" defense, described for <i>Crotalus</i> by Cowles (1938:13), when approached + by a king-snake, <i>Lampropeltis getulus</i>. In this unusual posture the anterior + and posterior portions of the body are held against the ground and the middle + one-fourth to one-third of the body is lifted up and used in striking the + intruder. This same defense posture also was observed in rattlesnakes when + presented with the odor of the spotted skunk, <i>Spilogale phenax</i>. However, the + "king-snake defense posture" is probably not a well-established behavioral + pattern in the cottonmouth, for it sometimes feeds upon king-snakes. I observed + the killing and devouring of a cottonmouth by a speckled king-snake, <i>L. g. holbrooki</i>; the only attempts to escape were by rapid crawling and biting.</p> +<p>Cottonmouths often squirt musk as a defensive action. The tail is switched + back and forth, and musk is emitted from glands on each side of the base of + the tail. The fine jets of musk are sprayed upward at about 45° angles for a + distance of nearly five feet. How often this defense mechanism is used against + other animals is not known, but the musky odor can frequently be detected in + areas where cottonmouths are common. The odor is repulsive and, if concentrated, + can cause nausea in some individuals. To me, the scent is indistinguishable + from that of the copperhead.</p> +<h3>"Head Bobbing"</h3> +<p>"Head bobbing" in snakes has been described frequently in the literature, + and many interpretations have been advanced to explain its occurrence. One + of the earlier accounts was that of Corrington (1929:72) describing behavior + of the corn snake, <i>Elaphe guttata</i>. Characteristic bobbing occurred when the + snake was cornered, and seemingly the purpose was to warn or frighten foes. + Neill (1949:114-115) mentioned the jerking or bobbing of the head in several + species of snakes including the cottonmouth, and remarked that "it is apparently <span class="pagenum"><a name="Page_472" id="Page_472">[472]</a></span> connected with courtship and with the recognition of individuals." + According to Munro (1950:88), "head bobbing" appears to be a sign of + annoyance in some instances but is usually concerned with reproduction and + individual recognition. Richmond (1952:38) thought that many types of + head movements among not only reptiles but also birds and some mammals + are a result of poor vision and serve "to delimit and orient an object that for + lack of motion is otherwise invisible." Head movements undoubtedly occur + in animals to facilitate accommodation, but it is obvious from Richmond's + conclusions that he has never observed "head bobbing" in snakes. The term + itself is grossly misleading and should be discarded. Mansueti (1946:98) + correctly described the movements as spastic contractions of the body. I have + observed numerous instances of these movements in cottonmouths, copperheads, + and rat snakes (<i>Elaphe obsoleta</i>); and in no case has the movement + resembled a head bob as is described in lizards and other animals. The movement + appears to be a result of a nervous or sexually excited state and consists + of highly spastic contractions confined to the anterior part of the snake most + of the time but affecting the entire body on some occasions.</p> +<p>I found the response to be most common among cottonmouths in confinement + when food was introduced to a cage containing several individuals + (increasing the tendency to strike at a moving object) and when an individual + was placed back in the cage after being handled. At these times the snakes + that were inactive began to jerk for a few seconds. When the snake is in + this seemingly nervous state, the same response is elicited by another snake + crawling over it. At other times the movement of one individual causes no + such response. The jerking movements appear to be released by the recognition + of a nervous state in another individual and may serve to protect the + jerking individual from aggressive advances of the former.</p> +<p>Where courtship is involved, the jerking motions are made in conjunction + with writhing of the male and do not result from the same type of releaser + described above.</p> +<h3>Combat Dance</h3> +<p>The so-called combat dance between male snakes has long been known, + but its significance is still poorly understood. It was for many years believed + to be courtship behavior until the participants were examined and found to + be males. Carr and Carr (1942:1-6) described one such instance in two + cottonmouths as courtship. In their observations, as well as those of others, + copulation was never observed following the "dance" but was assumed to be + the ultimate goal. After the discovery that only males participated, it was + suggested that combat involved competition for mates, but the "dance" has + been observed at times other than the breeding season (Ramsey, 1948:228).</p> +<p>Shaw (1948:137-145) discussed the combat of crotalids in some detail but + drew no conclusions as to the cause of the behavior. Lowe (1948:134) concluded + with little actual evidence that combat among male snakes is solely + for territorial purposes. Shaw (1951:167) stated that combat may occur as + a possible defense against homosexuality. One case of homosexual mating + among cottonmouths was reported (Lederer, 1931:651-653), but the incomplete + description seems to be of normal courtship procedure except that the + "female" tried to avoid the male. Two instances of combat observed between + timber rattlesnakes (<i>C. h. horridus</i>) by Sutherland (1958:23-24) were definitely <span class="pagenum"><a name="Page_473" id="Page_473">[473]</a></span> initiated because of competition for food. More observations are needed before + the significance of the combat can be fully understood.</p> +<hr class="chap" /> +<h2>THE VENOM</h2> +<h3>Properties of the Venom</h3> +<p>The venom and poison apparatus have developed primarily as a means of + causing rapid death in small animals that are the usual prey. As a protective + device against larger enemies, including man, the venom may have some + value; but this was probably unimportant in the evolution of the poison + mechanism. A secondary function of the venom is to begin digestion of tissues + of the prey. Since food is swallowed whole, injection of digestive enzymes + into the body cavity enhances digestion of the prey.</p> +<p>Kellogg (1925:5) described venom as a somewhat viscid fluid of a yellowish + color and composed of 50 to 70 per cent proteins, the chief remaining components + being water and carbohydrates, with occasional admixtures of abraded + epithelial cells or saprophytic microorganisms. Salts, such as chlorides, phosphates + of calcium, magnesium, and ammonium, occur in small quantities. Each + of the components of snake venom has a different effect on the body of the + victim. It was at first believed that there were two types of venoms: + neurotoxic, which acts upon nervous tissue; and haemotoxic, which acts on + blood and other tissues. It has since been found that venoms are composed + of varying mixtures of both types. Fairley (1929:301) described the constituents + of venom as: (1) neurotoxic elements that act on the bulbar and + spinal ganglion cells of the central nervous system; (2) hemorrhagins that + destroy the lining of the walls of blood vessels; (3) thrombose, producing + clots within blood vessels; (4) hemolysins, destroying red blood corpuscles; + (5) cytolysins that act on leucocytes and on cells of other tissues; (6) elements + that retard coagulation of the blood; (7) antibactericidal substances; + and (8) ferments that prepare food for pancreatic digestion. Elapid snakes + tend to have more of elements 1, 4, and 6 in their venoms, while viperids and + crotalids, of which the cottonmouth is one, have higher quantities of elements + 2, 3, and 5. Kellogg (<i>loc. cit.</i>) stated that venom of cottonmouths contains + more neurotoxin than that of rattlesnakes and not only breaks down the nuclei + of ganglion cells but also produces granular disintegration of the myelin sheath + and fragmentation of the conducting portions of nerve fibers.</p> +<p>Thus, venoms contain both toxic elements and non-toxic substances that + promote rapid spreading of the venom through the body of the victim. Jacques + (1956:291) attributed this rapid spreading to the hyaluronidase content of + venoms.</p> +<h3>Venom Yield and Toxicity</h3> +<p>One of the most important yet undeterminable factors of the gravity of + snakebite is the amount of venom injected into the victim. Since this volume + varies considerably in every bite, attempts have been made to determine the + amount and toxicity of venom produced by each species of poisonous snake. + Individual yield is so variable that a large number of snakes must be milked in + order to determine the average yield. Even then there remains an uncertainty + as to how this amount may compare with that injected by a biting snake.</p> +<p>Wolff and Githens (1939b:234) made 16 venom extractions from a group <span class="pagenum"><a name="Page_474" id="Page_474">[474]</a></span> of cottonmouths in a two-year period. The average yield per snake fluctuated + between 80 and 237 milligrams (actual weight), and toxicity measured as the + minimum lethal dose for pigeons varied from 0.05 to 0.16 milligrams (dry + weight). No decrease in yield or toxicity was evident during this period. + Another group of cottonmouths from which venom was extracted over a + period of five years also showed no decrease in yield or toxicity. Of 315 individual + extractions the average amount obtained from each individual was + 0.55 cubic centimeters of liquid or 0.158 grams of dried venom (28.0 per cent + solids). The minimum lethal dosage (M. L. D.) which was determined by + injecting intravenously into 350-gram pigeons was found to be 0.09 milligrams + (dry weight). Each snake carried approximately 1755 M. L. D.'s of venom.</p> +<p>The record venom extraction for the cottonmouth was 4.0 cubic centimeters + (1.094 grams dried venom) taken from a five-foot snake which had been in + captivity for 11 weeks and milked five weeks earlier (Wolff and Githens, + 1939a:52). The average yield of venom of cottonmouths is about three times + the average yield reported for copperheads by Fitch (1960:256), a difference + correlated with the greater bulk and relatively large head of the cottonmouth.</p> +<p>Allen and Swindell (1948:13) stated that cottonmouth venom rates third + in potency, compared drop for drop to that of <i>Micrurus fulvius</i> and <i>Crotalus + adamanteus</i>. Freshly dried cottonmouth venom tested on young white rats + showed the lethal dose to be from 23 to 29 milligrams per kilogram of body + weight. The venom of 11 one-week-old cottonmouths was found to be more + potent than that of adult males. Githens (1935:171) rated <i>C. adamanteus</i> venom as being weaker than that of the copperhead (<i>A. contortrix</i>), which he + rated only slightly lower than cottonmouth venom. The crotalids which he + ranked more toxic than cottonmouths are: the Pacific rattlesnake (<i>C. viridis + oreganus</i>) and the massasauga (<i>S. catenatus</i>). He found <i>A. bilineatus</i>, <i>C. + durissus</i>, and <i>C. v. lutosus</i> to have the same toxicity as cottonmouths. Minton + (1953:214) found that the intraperitoneal "lethal dose 50" (the dose capable + of killing half the experimental mice receiving injections of it) was 6.36 milligrams + per kilogram for copperheads. However, in later publications Minton + (1954:1079; 1956:146) reported that the "lethal dose 50" for copperheads was + 25.65 milligrams. Approximately the same potency was determined for cottonmouths. + Several rattlesnakes that he tested showed a higher toxicity than + copperheads or cottonmouths.</p> +<p>Criley (1956:378) found the venom of copperheads to be 6.95, nearer + Minton's earlier estimate, and rated cottonmouth venom as being twice as + toxic as that of copperheads. The relative toxicities of other crotalids tested, + considering the cottonmouth to be one unit, were: <i>C. basiliscus</i>, 0.3; <i>A. contortrix</i>, + 0.5; <i>C. viridis oreganus</i>, 1.4; <i>A. bilineatus</i>, 2.2; <i>C. adamanteus</i>, 2.3; <i>C. v. + viridis</i>, 3.2; <i>C. durissus terrificus</i>, 27.5.</p> +<p>It can be seen from the above examples that toxicity of venoms and the + resistance of the animal receiving an injection of venom is highly variable. + Possibly the venom of each species of snake has greatest effect on animals of + the particular group relied on for food by the snake. If that is so, the venom + of cottonmouths would be expected to be more toxic when tested on fish, + reptiles, and amphibians than on birds and mammals. Likewise, the venom + of most species of rattlesnakes would be expected to be more virulent when + injected into mammals than when injected into lower vertebrates. But, according + to Netting (1929:108), species of rattlesnakes that prey on cold-blooded <span class="pagenum"><a name="Page_475" id="Page_475">[475]</a></span> animals, which are less susceptible to venoms than warm-blooded + animals, are thought to have highly toxic venoms. This explanation accounts + for the powerful venom of <i>Sistrurus catenatus</i>; and, in this respect, venom of + cottonmouths should be highly toxic also. However, no clear-cut trends have + been shown in most cases. Allen (1937) injected 250-gram guinea pigs with + 4 milligrams of venom of various poisonous snakes. Survival time was recorded + in order to indicate the relative potency of the venoms. Of 16 such tests <i>C. + adamanteus</i> held places 1, 2, 3, 12, and 16; <i>Bothrops atrox</i> held places 4, 9, + 10, and 13; and <i>A. piscivorus</i> held places 5, 7, 8, and 15. Places 6, 11, and 14 + were held by three individuals of different species. No relationship to size + or sex was indicated by the results of this experiment.</p> +<h3>Susceptibility of Snakes</h3> +<p>Numerous experiments have been conducted to determine the susceptibility + of various snakes to venom. The majority of these experiments were performed + to learn whether or not venomous snakes were immune to their own + poison. Conant (1934:382) reported on a 30-inch cottonmouth that killed + two Pacific rattlesnakes and another cottonmouth. One rattlesnake was bitten + on the tail and the other on or near the head and partially swallowed. Gloyd + (1933:13-14) recorded fatal effects to a rattlesnake from the bite of a cottonmouth. + He also reported on the observations of three other crotalids bitten + by themselves or other snakes, from which no harmful effects were observed. + Allen (1937) injected several snakes with dried cottonmouth venom which + was diluted with distilled water just before each injection. Four cottonmouths + receiving 9, 18, 19, and 20 milligrams of venom per ounce of body weight survived, + while another receiving 18.7 milligrams per ounce died after three hours. + A specimen of <i>S. miliarius</i> receiving 8.3 milligrams per ounce died in about + ten hours, while a <i>C. durissus</i> receiving 12.5 milligrams per ounce succumbed + in 45 minutes. An alligator receiving 6 milligrams per ounce died in 14 hours. + Even the snakes that survived showed some degree of swelling.</p> +<p>The studies of Keegan and Andrews (1942:252) show that king-snakes are + sometimes killed by poisonous snakes. A <i>Lampropeltis calligaster</i> injected with <i>A. contortrix</i> venom (0.767 milligrams per gram) died five days following the + injection. This amount was more than twice the amount of <i>A. piscivorus</i> venom injected into a <i>L. getulus</i> by Allen (1937) in which the snake showed + no ill effects. Keegan and Andrews (<i>loc. cit.</i>) stated that success in overpowering + and eating poisonous snakes by <i>Lampropeltis</i> and <i>Drymarchon</i> may be due + to the ability to avoid bites rather than to immunity to the venom. However, + Rosenfeld and Glass (1940) demonstrated that the plasma of <i>L. g. getulus</i> had an inhibiting effect on the hemorrhagic action on mice of the venoms of + several vipers.</p> +<p>One of the more extensive studies on effects of venoms on snakes is that + by Swanson (1946:242-249). In his studies freshly extracted liquid venom + was used. His studies indicated that snakes are not immune to venom of + their own kind or to closely related species. Copperhead venom killed copperheads + faster than did other venoms but took more time to kill massasaugas, + cottonmouths, and timber rattlers. However, most of the snakes were able to + survive normal or average doses of venom although they are not necessarily + immune to it.</p> +<p><span class="pagenum"><a name="Page_476" id="Page_476">[476]</a></span></p> +<p>One of the major problems in comparing the data on toxicity of venom + in studies of this type is that no standard method of estimating toxicity has + been used. Swanson's (<i>loc. cit.</i>) amount of venom equalling one minim + (M.L.D.?) ranged from 0.058 to 0.065 cubic centimeters. There were no + different values given for each species, but the time that elapsed from injection + of the venom to death represented the toxicity. There also was no attempt + in his study to convert the amount of venom used into a ratio of the volume + of venom per weight of snake, making the results somewhat difficult to interpret. + Additional work in this field should provide for many injections into + many individuals of several size classes. The studies to date have been on + far too few individuals to allow statistical analyses to be accurate.</p> +<hr class="chap" /> +<h2>THE BITE</h2> +<h3>Effects of the Bite</h3> +<p>Factors determining the outcome of snakebite are: size, health, and species + of snake; individual variation of venom toxicity of the species; age and size + of the victim; allergic or immune responses; location of the bite; and the + amount of venom injected and the depth to which it is injected. The last + factor is one of the most variable, owing to (1) character and thickness of + clothing between the snake and the victim's skin, (2) accuracy of the snake's + strike, and (3) size of the snake, since a large snake can deliver more venom + and at a greater depth than can a small snake.</p> +<p>Pope and Perkins (1944) demonstrated that pit-vipers of the United States + bite as effectively as most innocuous snakes and that a careful study of the + bite may reveal the location of the pocket of venom, size of the snake, and + possibly its generic identity (see Dentition). The bite pattern of the cottonmouth + as well as the other crotalids showed the typical fang punctures plus + punctures of teeth on both the pterygoid and mandible. Even so, a varying + picture may be presented because from one to four fang marks may be present. + At times in the fang-shedding cycle three and even four fangs can be in + operation simultaneously.</p> +<p>Various authors have attributed death of the prey to the following causes: + paralysis of the central nervous system, paralysis of the respiratory center, + asphyxiation from clotting of the blood, stoppage of the heart, urine suppression + due to crystallized hemoglobin in the kidney tubules, dehydration of + the body following edema in the area of the bite, or tissue damage. Mouths + of snakes are reservoirs for infectious bacteria, which are especially prolific in + damaged tissue. Bacterial growth is aided by the venom which blocks the + bactericidal power of the blood.</p> +<p>Three grades in the severity of snakebite (I, minimal; II, moderate; and + III, severe) were described by Wood, Hoback, and Green (1955). Parrish + (1959:396) added a zero classification to describe the bite of a poisonous + snake in which no envenomation occurred. Grade IV (very severe) was + added by McCollough and Gennaro (1963:961) to account for many bites + of the eastern and western diamondback rattlesnakes.</p> +<p>The first symptom of poisonous snakebite is an immediate burning sensation + at the site of the bite. Within a few minutes the loss of blood into the tissues + causes discoloration. Swelling proceeds rapidly and can become so great as + to rupture the skin. Pain is soon felt in the lymph ducts and glands. Weakness, <span class="pagenum"><a name="Page_477" id="Page_477">[477]</a></span> nausea, and vomiting may ensue at a relatively early stage. Loss of + blood into tissues may spread to the internal organs. In conjunction with a + rapid pulse, the blood pressure and body temperature can drop. Some difficulty + in breathing can occur, especially if large amounts of neurotoxin are + present in the venom. In severe cases the tension due to edema obstructs + venous and even arterial flow, in which case bacteria may multiply rapidly in + the necrotic tissue and gangrene can occur. Blindness due to retinal hemorrhages + may occur. Symptoms of shock may be present after any bite.</p> +<h3>Treatment</h3> +<p>Perhaps one of the most important factors in the outcome of snakebite is + the treatment. Because of the variable reactions to snakebite, treatment + should vary accordingly. Many methods have been proposed for treating + snakebite, and there is disagreement as to which is the best. The list of + remedies that have been used in cases of snakebite includes many that add + additional injury or that possibly increase the action of the venom. The use + of poultices made by splitting open living chickens and the use of alcohol, + potassium permanganate, strychnine, caffeine, or injection of ammonia have + no known therapeutic value, and may cause serious complications. The most + important steps in the treatment of snakebite are to prevent the spread of + lethal doses of venom, to remove as much venom as possible, and to neutralize + the venom as quickly as possible.</p> +<p>It is generally agreed that the first step in snakebite treatment should be + to place a ligature above the bite to restrict the flow of venom, and also to + immobilize the patient as much as possible. The ligature should be loosened + at least every fifteen minutes. The next steps are sterilization of the skin and + the making of an incision through the fang punctures. As pointed out by + Stahnke (1954:8), the incision should be made in line with the snake's body + at the time of the bite, so as to account for the rearward curvature of the fangs + and possibly to reach the deposition of venom. Many instruction booklets + and first-aid guides have specified the length and depth of incision to be + made, but the actual size and depth of the cut should depend upon the location + of the bite. An "X" cut or connection of the fang punctures is likely to + facilitate the spread of the venom. No cut should be made that would sever + a large blood vessel or ligament.</p> +<p>Extensive damage is often caused by well-meaning individuals whose attempts + at first aid result in brutally deep incisions and tourniquets applied too + tightly and for too long a period of time; the resultant damage in many instances + exceeds that of the bite itself (Stimson and Engelhardt, 1960:165). + Stimson and Engelhardt also think that time should be sacrificed to surgical + cleanliness, and incisions should not be made if a hospital can be reached + within an hour.</p> +<p>The ligature-cryotherapy (L-C) method proposed by Stahnke (1953) has + been severely criticized by other workers. He stated that the ligature should + be tight enough to restrict completely the flow of venom until the temperature + of the area can be lowered sufficiently to prevent any action of the venom. + After 10 minutes the ligature may be removed and the bitten area kept immersed + in a vessel of crushed ice and water. If the envenomized member is + to be treated for more than four hours (which is the case with almost all <span class="pagenum"><a name="Page_478" id="Page_478">[478]</a></span> pit-viper bites), it should be protected by placing it in a plastic bag. The + venom action should be tested after 12 or more hours. This consists of a brief + warming period to determine whether or not the action of the venom can be + felt. The patient should be kept warm at all times; and the warming at the + termination of treatment should be done gradually, preferably by allowing + the water to warm slowly to room temperature.</p> +<p>Advocates of the L-C method warn against making incisions unless they + are absolutely necessary, the theory being that each cut permits additional + bacterial infection and does little good in removing venom. However, McCollough + and Gennaro (1963:963) demonstrated that, in bites where the + fangs had only slightly penetrated the skin, more than 50 per cent of the + venom was removed in some instances if suction was started within three + minutes after the injection. With deeper injection the amount of venom + recovered sometimes reached 20 per cent of the dose. Stahnke suggested that + an incision be made at the site of the bite only after the site has been + refrigerated for at least 30 minutes.</p> +<p>Stimson and Engelhardt (<i>loc. cit.</i>) stated that two constricting bands + should be used between the bite and the body and that cracked ice in a cloth + should be applied to the bite before reaching a hospital. In addition, they + suggested the following procedure. Rings of incisions should follow the swelling, + and suction should continue for several hours. After the edema has + receded, the limb should be wrapped in a towel containing crushed ice. + Antivenin should be given only in severe cases. Calcium gluconate and gas + gangrene antitoxin as well as antibiotics are helpful.</p> +<p>The most recent and up-to-date summary of snakebite treatment is that by + McCollough and Gennaro (1963). Following is a brief summary of their + suggestions:</p> +<p>1. Immobilization—Systemic immobilization is effected by body rest and + locally by splinting the bitten area.</p> +<p>2. Tourniquet—A lightly occlusive tourniquet during a 30- to 60-minute + period of incision and suction would seem to possess some advantages. In + severe cases where medical attention is hours away, a completely occlusive + tourniquet may be necessary to prevent death. Sacrifice of the extremity may + be necessary for the preservation of life.</p> +<p>3. Incision and suction—Suction should begin three to five minutes after + injection of venom if symptoms of poisoning are present. Incisions one-fourth + inch to an inch long across each fang mark should be made in order to open + the wound for more efficient suction. Multiple incisions are not useful for the + removal of venom but may be employed under hospital conditions to reduce + subcutaneous tensions and ischemia.</p> +<p>4. Cryotherapy—An ice cap over the site of the bite for relief of pain + would seem to be permissible, especially prior to the administration of antivenin. + It must be remembered that cooling during the administration of the antivenin + radically reduces the access of the antiserum to the bite area.</p> +<p>5. Antivenin—Antiserum is the keystone to the therapy of snakebite. Careful + evaluation of the severity of the bite and the patient's sensitivity should be + made before the use of antivenin. In Grade II (moderate) bites, the intramuscular + injection on the side of the bite may suffice. In Grades III (severe) + and IV (very severe), shock and systemic effects require intravenous injection. + In bites producing symptoms of this severity, antivenin must be given in <span class="pagenum"><a name="Page_479" id="Page_479">[479]</a></span> amounts large enough to produce clinical improvement. Ten to 20 units may + be necessary to prevent the relapse that sometimes occurs after small doses + of antivenin. Permanent remission of swelling and interruption of necrosis are + the therapeutic end point in the clinical use of the antiserum.</p> +<p>In all cases of snakebite where there is any doubt as to the snake's identity, + it should be killed if possible and taken to the hospital for positive identification. + In many instances of actual bites by poisonous snakes the only treatment + needed was an injection of tetanus antitoxin or toxoid and sedation, because + physical examination revealed no indication of poisoning (Stimson and Engelhardt, <i>loc. cit.</i>).</p> +<h3>Case History of a Bite</h3> +<p>On July 29, 1963, at 8:20 a.m., I was treating a nine-month-old cottonmouth + for mites. As I dropped the snake into a sink, it twisted its head and + bit the tip of my right middle finger with one fang. The fang entered just + under the fingernail and was directed downward, the venom being injected + about five millimeters below the site of fang penetration. After placing the + snake back in its cage, I squeezed the finger once to promote bleeding, wrapped + a string around the base of the finger, and drove to Watkins Memorial Hospital + on the University of Kansas campus. I began to feel a burning sensation in the + tip of the finger almost immediately. Upon my arrival at the hospital, an additional + ligature was placed around my wrist. At 8:30 a.m. a small incision + was made in the end of the finger, which by this time was beginning to darken + at the point of venom deposition. I sucked on the finger until 8:35 a.m., + when a pan of ice water that I had requested was brought to me. No pain + was felt except that caused by the ice. Fresh ice was added as needed to + keep the temperature low. By 9:30 a.m. the finger had swollen and stiffened. + At 10:00 a.m. the swelling had progressed to the index finger and back of + the hand. I experienced difficulty in opening and closing the hand. Blood + oozed slowly from the incision. A dull ache persisted and about every two + to four minutes a sharp throb could be felt until nearly 11:00 a.m., when the + pain diminished. The rate and intensity of throbbing increased whenever the + hand was removed from the ice bath for more than a few seconds. Although + only the hand was immersed, the entire forearm was cold. Pain was felt along + the lymphatics on top of the arm when it was touched, and by 1:00 p.m. a + slight pain could be felt in the armpit. Since swelling and pain were almost + nonexistent by 2:00 p.m., I was permitted to leave. After walking to a nearby + building, I again felt a burning sensation as the hand warmed. I made + another ice bath and again immersed the hand in it until 4:10 p.m., at which + time it was removed from the water. The pain and swelling began anew, and + the hand was placed back in an ice bath from 5:30 p.m. until about 7:30 p.m. + At this time cryotherapy was discontinued. From 10:00 p.m. to + 12:00 midnight my legs twitched periodically, and pain could be felt in both + armpits. A slight difficulty in breathing also was experienced for a short time. + The acute pain and burning sensation remained in the finger until the following + morning, but swelling progressed only as far as the wrist. The only discomfort + that day was in the finger. The tip was darkened, the entire first + digit red and feverish, and the lymphatics still painful when touched. By the + third day the swelling had regressed. The incision itself was the main cause + of discomfort, and the soreness at the site of the bite persisted for at least four + days.</p> +<p>Although the L-C method of snakebite treatment has been vigorously attacked + by many, there is still need of much more data before it can be unequivocally + condemned or praised. It was preferred in the treatment of this + bite because: I knew that envenomation was minimal and that there would be + no need for antivenin; only one fang of a snake less than one foot long had + entered the tip of the finger; the snake had bitten three frogs in the previous <span class="pagenum"><a name="Page_480" id="Page_480">[480]</a></span> two days and had possibly used up a considerable amount of its venom; the + venom was deposited at such a shallow depth that at least a portion of it + could be removed by suction; and the wound bled freely even before suction + was applied. The ice water was uncomfortably cold but was not cold enough + to cause frostbite, a major objection to the L-C method. Ideally, fresh ice + should be added little by little to replace that which is melting, and the immersed + area should be protected from the water by a plastic bag. Pain and + swelling can be minimized by cryotherapy, but I would recommend its use + only in cases of mild poisoning such as the one described herein.</p> +<h3>Snakebite in the United States</h3> +<p>Many estimates have been made of the number of bites of poisonous snakes + that occur annually in the United States. The occurrence of poisonous snakebite + has been nearly as badly underestimated as fatal results of their envenomations + have been overrated. For important data on number of persons bitten + by poisonous snakes in the United States, see the following: Allen and + Swindell (1948:15); Githens (1935:172); Klauber (1956:811); Parrish (1963); + Sowder and Gehres (1963:973); Stimson and Engelhardt (1960:153); Swaroop + and Grab (1956:441); Swartzwelder (1950:579); Willson (1908:530); and + Wood (1954b:937).</p> +<p>Judging from estimates made in several states, the number of poisonous + snakebites in the United States would be about 5000 per year. In the region + where the cottonmouth occurs there are approximately 2000 persons bitten + annually by poisonous snakes. Of these approximately 39 per cent are copperhead + bites, 30 per cent each are cottonmouth and rattlesnake bites, and I per + cent are coral snake bites. These percentages vary considerably from place + to place, because of the distribution and abundance of the eight species of + poisonous snakes whose ranges overlap that of the cottonmouth.</p> +<p>According to Parrish (1963), about 14 people die of snakebite each year in + the United States. Of these deaths, about 6.6 per cent are attributable to + cottonmouths, 77.0 per cent to rattlesnakes, and 1.6 per cent to coral snakes; + 14.8 per cent are unidentified. Almost half of the fatalities are in persons + less than 20 years of age, the high mortality rate being partially due to the + greater ratio of venom to body weight.</p> +<hr class="chap" /> +<h2>SUMMARY</h2> +<p>In my study, 306 living and preserved cottonmouths were examined. + This species occurs throughout the coastal plains of the + southeastern United States, usually at altitudes of less than 500 feet + but occasionally up to altitudes of more than 2000 feet.</p> +<p>Two subspecies are recognized: the eastern cottonmouth, <i>A. p. + piscivorus</i>, occurring from extreme eastern Mississippi to southeastern + Virginia and Florida; and the western cottonmouth, <i>A. p. + leucostoma</i>, occurring from eastern Mississippi northward to southern + Illinois and Missouri and westward to central Texas. Intergradation + occurs in eastern Mississippi.</p> +<p><span class="pagenum"><a name="Page_481" id="Page_481">[481]</a></span></p> +<p>The northern edge of the range is probably limited by low temperatures + in winter, and the western edge by lack of available + habitat resulting from insufficient precipitation. Old records of occurrence + indicate that the range has decreased in the last 100 years. + The species inhabits mostly areas where water is found, but at times + wanders a mile or more from the nearest water.</p> +<p>The ground color is predominantly a brown, but varies from a + brownish-green to almost black with a pattern of 10 to 17 irregular + bands of a darker shade of brown. The pattern is better defined in + the eastern subspecies than in the western.</p> +<p>The scutellation resembles that of other species of <i>Agkistrodon</i>. + In the specimens examined supralabials ranged from 7 to 9, and + infralabials from 8 to 12. The number of dorsal scale rows on the + neck, at mid-body, and immediately anterior to the anus is relatively + constant at 27-25-21, respectively. Ventral scales of 34 males averaged + 134.4 (128 to 139), and those of 48 females 133.5 (128 to 137). + The number of caudal scales showed some degree of sexual dimorphism; + the average was 45.4 (41 to 50) in 34 males and 42.6 + (39 to 49) in 44 females. In general, caudal scales on the basal + half of the tail are undivided, whereas those on the distal half are + divided. No marked geographical variation was found in any scale + character.</p> +<p>The poison fangs vary in length from 1.3 per cent of snout-vent + length in juveniles to 1.0 per cent in large adults. Fangs of + captive cottonmouths were shed and replaced at intervals of about + 21 days, but the interval was variable. Relationships in distance + between the base of fangs and between fang punctures in an actual + bite indicate that examination of the wound does not provide a + good basis for judging accurately the size of the snake that inflicted + the bite.</p> +<p>In general, females less than 450 millimeters in snout-vent length + were juveniles; those more than 450 millimeters were classified as + post partum or reproductive on the basis of sizes of ovarian follicles. + Since about half the adult females were fecund, it was concluded + that a biennial reproductive cycle occurs in this species. An annual + cycle may occur in areas where temperature permits year-round + activity. It was estimated that females become sexually mature at + an age of approximately two and one-half years. Mating is probably + most concentrated in early spring at about the time when females + ovulate, but copulation is not a stimulus for ovulation. Sperm + retention and delayed fertilization allow young to be produced without <span class="pagenum"><a name="Page_482" id="Page_482">[482]</a></span> copulation occurring in each breeding season. The testes increase + in size gradually rather than rapidly at maturity or in each + breeding season, but seasonal cycles in sperm production occur.</p> +<p>The gestation period is three and one-half to four months. Determination + of sex in the embryos is possible by late June, because + the hemipenes of males are evaginated until the time of birth. + Parturition generally occurs in August or September, but captivity + may delay birth for a month or more. From one to 16 young per + litter are born, depending on size of the mother and other factors; + but the average is between six and seven. Mortality rate at birth is + high in captive individuals but has not been determined in natural + populations. The sex ratio in embryos and adults examined revealed + about 53 per cent females. Because sufficient information on + population composition is not available, an estimate of the percentage + of adults in a natural population was based upon the number + found in my study. The reproductive potential was estimated + from these figures.</p> +<p>Normal young at birth are 230 to 240 millimeters in snout-vent + length, but their size is influenced by the condition of the mother. + Comparison of newborn young with those captured in spring + indicates that little growth occurs during winter. Early growth is + largely dependent upon feeding before winter quiescence.</p> +<p>The umbilical cord is broken at birth and the navel closes within + a few days, but the scar remains throughout life. Sexual dimorphism + in the position of the scar is characteristic of some snakes but is + minimal in cottonmouths.</p> +<p>In those snakes more than 700 millimeters in length, males outnumber + females three to one. The maximum age of cottonmouths + in nature is unknown, but one has been kept in captivity for more + than 18 years.</p> +<p>Allometric growth is striking in cottonmouths. The head and + tail are proportionately longer in young individuals than in adults; + and in males the tail is, on the average, slightly longer than in + females of the same size.</p> +<p>Shedding of the skin provides for growth and wear in snakes. + The young shed within a few days after birth and generally shed + more frequently than adults. Frequency of shedding depends + mostly on amount of food consumed, and there is some evidence + that injuries on the head and neck increase the frequency of shedding. + Before shedding, the eyes become cloudy for about five <span class="pagenum"><a name="Page_483" id="Page_483">[483]</a></span> and one-half days, then clear up again for about four days before + the skin is shed.</p> +<p>The food of cottonmouths consists mainly of small vertebrates + and occasionally invertebrates that are found near water. Fish, + amphibians, and reptiles make up nearly 70 per cent of the diet. + Carrion is also eaten and cannibalism occurs occasionally. Food + is obtained by lying in ambush or by active searching. The young + are known to lure their prey within striking range by waving their + yellow tails in a manner suggestive of writhing grubs. The method + of obtaining prey differs according to the kind of prey. Generally, + cottonmouths retain their hold on fish or frogs but release mice + and larger prey after delivering a bite.</p> +<p>The major causes of mortality of cottonmouths are obscure. + Predators are known to include alligators, indigo snakes, king-snakes, + largemouth bass, and blue herons; there are probably + numerous others. Heavy parasitic infestations were found among + the snakes examined. Snake mites, <i>Ophionyssus natricus</i>, became + increasingly abundant on almost all captive snakes in April and + May of 1963. Lung flukes (<i>Ochetosoma</i> sp.) were in 16 of 20 + captive snakes, and many preserved specimens contained nematodes + (<i>Kalicephalus</i> sp.) in the stomach and/or tapeworms (<i>Ophiotaenia</i> sp.) in the intestine. Although parasitic infestation causes discomfort + and may lower resistance to other detrimental factors, it + is difficult to attribute death to the effect of any particular kind + of parasite. Miscellaneous causes of death of some captive snakes + also were discussed.</p> +<p>The maximal body temperatures tolerated by four cottonmouths + were between 38° and 40° C., but a temperature of 38° was lethal + to a fifth individual. Cottonmouths have been found on occasion + when other snakes were inactive because of low temperatures, but + minimal temperatures tolerated by this species are not known. The + annual cycle of activity is dependent upon temperature and thus + varies from north to south. Cottonmouths generally migrate inland + in autumn, usually to dry forested hillsides, where they den along + with other species of snakes. After a few warm days in spring + they migrate back to the water's edge. The diel activity cycle likewise + depends upon temperatures but is influenced by other factors + as well. In spring and autumn, the snakes are active mostly on + warm, sunny days, whereas in summer they are active mostly at + night. In order to maintain adequate internal temperatures, much <span class="pagenum"><a name="Page_484" id="Page_484">[484]</a></span> time is spent basking mostly in a characteristic flat, resting coil + either beside a body of water or above water on limbs of dead + trees. In this position the snake is ready either for a short strike + or a hasty getaway.</p> +<p>Juveniles appear particularly aggressive and strike repeatedly + when approached, a behavioral pattern definitely favoring survival. + Adults vary in disposition, usually appearing sluggish and lazy, + but they are capable of striking rapidly when disturbed. The typical + threat display consists of lying in a coiled position with the mouth + opened widely, exposing the white interior, and with the tail vibrating + rapidly. The striking posture resembles the resting coil except + that the anterior part of the body is raised off the ground and the + mouth is sometimes opened. Musk is often ejected in a fine spray + from glands in the tail as a further defensive action.</p> +<p>"Head bobbing," more properly described as spastic contractions + of the body, was observed in captives when food was introduced + into a cage containing several individuals or when one of the + snakes was returned to the cage after being handled. Reports in + the literature also have connected these jerking movements with + courtship. The response appears to be elicited whenever a nervous + state is recognized in another individual and may serve to protect + the jerking individual from aggressive advances of the former.</p> +<p>The relatively heavy appearance of the body, sluggish habits, + and cryptic coloration are correlated with the development of + venom and fangs. The poison apparatus has developed primarily + as a means of causing rapid death in prey and secondarily, perhaps, + to begin the digestion of small animals that are the usual prey, but + it is also important as a defensive device. The venom contains at + least eight constituents that aid in its action on prey. Toxicity of + the venom is difficult to determine because of numerous variables, + but cottonmouth venom is generally believed to be less potent + than that of most rattlesnakes and more potent than that of the + copperhead. Snakes in general are more resistant to snake venoms + than other vertebrates of similar size, but there is no immunity + even to their own venom.</p> +<p>About ten per cent of the approximately 5000 bites of poisonous + snakes per year in the United States are attributable to cottonmouths, + and about seven per cent of the approximately 14 deaths + per year are caused by cottonmouths.</p> +<hr class="chap" /> +<p><span class="pagenum"><a name="Page_485" id="Page_485">[485]</a></span></p> +<h2><a name="LITERATURE_CITED" id="LITERATURE_CITED"></a>LITERATURE CITED</h2> +<p><span class="smcap">Allen, E. R.</span></p> +<blockquote> + <p>1937. Florida snake venom experiments. Florida Acad. Sci., 2:7 pp.</p> +</blockquote> +<p><span class="smcap">Allen, E. R.</span>, and <span class="smcap">Swindell, D.</span></p> +<blockquote> + <p>1948. Cottonmouth moccasin of Florida. Herpetologica, 4:1-16 (first + supplement).</p> +</blockquote> +<p><span class="smcap">Allen, M. J.</span></p> +<blockquote> + <p>1932. A survey of the amphibians and reptiles of Harrison County, Mississippi. + Amer. Mus. Novit., 542:1-20.</p> +</blockquote> +<p><span class="smcap">Anderson, P.</span></p> +<blockquote> + <p>1941. The cottonmouth in northern Missouri. Copeia, 1941(3):178.</p> + <p>1945. New herpetological records for Missouri. Bull. Chicago Acad. + Sci., 7(5):271-275.</p> +</blockquote> +<p><span class="smcap">Anon.</span></p> +<blockquote> + <p>1953. Snake collecting hobby of Colonial Heights lad. Virginia Wildlife, + 14-24.</p> +</blockquote> +<p><span class="smcap">Auffenberg, W.</span></p> +<blockquote> + <p>1963. The fossil snakes of Florida. Tulane Studies Zool., 10(3):131-216, + 51 figs.</p> +</blockquote> +<p><span class="smcap">Bailey, R. M.</span></p> +<blockquote> + <p>1948. Winter mortality in the snake <i>Storeria dekayi</i>. Copeia, 1948(3): + 215.</p> +</blockquote> +<p><span class="smcap">Barbour, R. W.</span></p> +<blockquote> + <p>1956. A study of the cottonmouth, <i>Agkistrodon piscivorus leucostoma</i> Troost, in Kentucky. Trans. Kentucky Acad. Sci., 17(1):33-41, + 1 fig.</p> +</blockquote> +<p><span class="smcap">Blanchard, F. N.</span></p> +<blockquote> + <p>1922. The amphibians and reptiles of western Tennessee. Occ. Pap. + Mus. Zool.; Univ. Michigan, 117:1-18.</p> +</blockquote> +<p><span class="smcap">Bogert, C. M.</span></p> +<blockquote> + <p>1943. Dentitional phenomena in cobras and other elapids with notes on + adaptive modifications of fangs. Bull. Amer. Mus. Nat. Hist., + 81(3):285-360.</p> +</blockquote> +<p><span class="smcap">Brattstrom, B. H.</span></p> +<blockquote> + <p>1954. The fossil pitvipers (Reptilia: Crotalidae) of North America. + Trans. San Diego Soc. Nat. Hist., 12(3):31-46, 2 figs.</p> +</blockquote> +<p><span class="smcap">Brown, A. E.</span></p> +<blockquote> + <p>1903. Texas reptiles and their faunal relations. Proc. Acad. Nat. Sci. + Philadelphia, pp. 543-558.</p> +</blockquote> +<p><span class="smcap">Carpenter, C. C.</span></p> +<blockquote> + <p>1958. Reproduction, young, eggs, and food of Oklahoma snakes. Herpetologica, + 14:113-115.</p> +</blockquote> +<p><span class="smcap">Carr, A. F., Jr.</span></p> +<blockquote> + <p>1936. The gulf-island cottonmouths. Proc. Florida Acad. Sci., 1:86-90.</p> +</blockquote> +<p><span class="smcap">Carr, A. F., Jr.</span>, and <span class="smcap">Carr, M. H.</span></p> +<blockquote> + <p>1942. Notes on the courtship of the cottonmouth moccasin. Proc. New + England Zool. Club, July 18, 20:1-6.</p> +</blockquote> +<p><span class="smcap">Clark, R. F.</span></p> +<blockquote> + <p>1949. Snakes of the hill parishes of Louisiana. Jour. Tennessee Acad. + Sci., 24(4):244-261.</p> +</blockquote> +<p><span class="pagenum"><a name="Page_486" id="Page_486">[486]</a></span></p> +<p><span class="smcap">Conant, R.</span></p> +<blockquote> + <p>1933. Three generations of cottonmouths, <i>Agkistrodon piscivorus</i> (Lacépède). + Copeia, 1933(1):43.</p> + <p>1934. Two rattlesnakes killed by a cottonmouth. Science, 80(2078):382.</p> + <p>1958. A field guide to reptiles and amphibians. Houghton Mifflin Co., + Boston, 366 pp.</p> +</blockquote> +<p><span class="smcap">Cook, F. A.</span></p> +<blockquote> + <p>1962. Snakes of Mississippi. Mississippi Game and Fish Comm., Surv. + Bull., ii + 45 pp.</p> +</blockquote> +<p><span class="smcap">Corrington, J. D.</span></p> +<blockquote> + <p>1929. Herpetology of the Columbia, South Carolina region. Copeia, + 1929:58-83.</p> +</blockquote> +<p><span class="smcap">Cowles, R. B.</span></p> +<blockquote> + <p>1938. Unusual defense postures assumed by rattlesnakes. Copeia, + 1938(1):13.</p> +</blockquote> +<p><span class="smcap">Cowles, R. B.</span>, and <span class="smcap">Bogert, C. M.</span></p> +<blockquote> + <p>1944. A preliminary study of the thermal requirements of desert reptiles. + Bull. Amer. Mus. Nat. Hist., 83(5):263-296.</p> +</blockquote> +<p><span class="smcap">Criley, B. R.</span></p> +<blockquote> + <p>1956. Development of a multivalent antivenin for the family Crotalidae. + Pp. 373-380 <i>in</i> Venoms (ed. Buckley, E. E., and Porges, N., Amer. + Assoc. Adv. Sci., Publ. No. 44).</p> +</blockquote> +<p><span class="smcap">Darlington, P. J.</span></p> +<blockquote> + <p>1957. Zoogeography: the geographical distribution of animals. John + Wiley and Sons, Inc., New York, xi + 675 pp.</p> +</blockquote> +<p><span class="smcap">Davis, D. D.</span></p> +<blockquote> + <p>1936. Courtship and mating behavior in snakes. Zool. Series Field Mus. + Nat. Hist., 20:257-290, figs. 28-34.</p> +</blockquote> +<p><span class="smcap">Didisheim, P.</span>, and <span class="smcap">Lewis, J. H.</span></p> +<blockquote> + <p>1956. Fibrinolytic and coagulent activities of certain snake venoms and + proteases. Proc. Soc. Exp. Biol. Med., 93(1):10-13.</p> +</blockquote> +<p><span class="smcap">Ditmars, R. L.</span></p> +<blockquote> + <p>1915. The reptile book. Doubleday, Page and Co., Garden City, N. Y., + xxxii + 472 pp.</p> + <p>1945. The reptiles of North America. Doubleday, Doran and Co., Inc., + Garden City, N. Y., xvi + 476 pp., 135 pls.</p> +</blockquote> +<p><span class="smcap">Dowling, H. G.</span></p> +<blockquote> + <p>1951a. A proposed standard system of counting ventrals in snakes. British + Jour. Herp., 1(5):97-98, 1 fig.</p> + <p>1951b. A proposed method of expressing scale reductions in snakes. + Copeia, 1951(2):131-134.</p> +</blockquote> +<p><span class="smcap">Dundee, H. A.</span>, and <span class="smcap">Burger, W. L., Jr.</span></p> +<blockquote> + <p>1948. A denning aggregation of the western cottonmouth. Nat. Hist. + Misc., Chicago Acad. Sci., 21:1-2.</p> +</blockquote> +<p><span class="smcap">Edgren, R. A.</span></p> +<blockquote> + <p>1951. The umbilical scar, a sexually dimorphic character in <i>Heterodon + platyrhinos</i>. Nat. Hist. Misc., 83:1-2.</p> +</blockquote> +<p><span class="smcap">Fairley, N. H.</span></p> +<blockquote> + <p>1929. The present position of snake bite and the snake bitten in Australia. + Med. Jour. Australia, 1(10):296-313.</p> +</blockquote> +<p><span class="pagenum"><a name="Page_487" id="Page_487">[487]</a></span></p> +<p><span class="smcap">Fitch, H. S.</span></p> +<blockquote> + <p>1956. Temperature responses in free-living amphibians and reptiles in + northeastern Kansas. Univ. Kansas Publ. Mus. Nat. Hist., 8(7):417-476, + 10 figs., 6 tables.</p> + <p>1960. Autecology of the copperhead. Univ. Kansas Publ. Mus. Nat. Hist., + 13(4):85-288, pls. 13-20, 26 figs.</p> +</blockquote> +<p><span class="smcap">Force, E. R.</span></p> +<blockquote> + <p>1930. The amphibians and reptiles of Tulsa County, Oklahoma, and + vicinity. Copeia, 1930(2):25-39.</p> +</blockquote> +<p><span class="smcap">Fox, W.</span></p> +<blockquote> + <p>1948. Effect of temperature on development of scutulation in the garter + snake, <i>Thamnophis elegans atratus</i>. Copeia, 1948(4):252-262.</p> +</blockquote> +<p><span class="smcap">Githens, T. S.</span></p> +<blockquote> + <p>1935. Studies on the venoms of North American pit vipers. Jour. Immun., + 29(2):165-173.</p> +</blockquote> +<p><span class="smcap">Glissmeyer, H. R.</span></p> +<blockquote> + <p>1951. Symposium. A snake den in Tooele County, Utah. Egg production + of the great basin rattlesnake. Herpetologica, 7(1):24-27.</p> +</blockquote> +<p><span class="smcap">Gloyd, H. K.</span></p> +<blockquote> + <p>1933. On the effects of moccasin venom upon a rattlesnake. Science, + 78(2010):13-14.</p> + <p>1934. Studies on the breeding habits and young of the copperhead, <i>Agkistrodon mokasen</i> Beauvois. Papers Michigan Acad. Sci., Arts + and Letters, 19:587-604.</p> +</blockquote> +<p><span class="smcap">Gloyd, H. K.</span>, and <span class="smcap">Conant, R.</span></p> +<blockquote> + <p>1943. A synopsis of the American forms of <i>Agkistrodon</i> (copperheads and + moccasins). Bull. Chicago Acad. Sci., 7(2):147-170, 16 figs.</p> +</blockquote> +<p><span class="smcap">Goodman, J. D.</span></p> +<blockquote> + <p>1958. Material ingested by the cottonmouth, <i>Agkistrodon piscivorus</i>, at + Reelfoot Lake, Tennessee. Copeia, 1958(2):149.</p> +</blockquote> +<p><span class="smcap">Guidry, E. V.</span></p> +<blockquote> + <p>1953. Herpetological notes from southeastern Texas. Herpetologica, 9:49-56.</p> +</blockquote> +<p><span class="smcap">Hall, H. H.</span>, and <span class="smcap">Smith, H. M.</span></p> +<blockquote> + <p>1947. Selected records of reptiles and amphibians from southeastern + Kansas. Trans. Kansas Acad. Sci., 49(4):447-454.</p> +</blockquote> +<p><span class="smcap">Hamilton, W. J., Jr.</span>, and <span class="smcap">Pollack, J. A.</span></p> +<blockquote> + <p>1955. The food of some crotalid snakes from Fort Benning, Georgia. + Nat. Hist. Misc., 140:1-4.</p> +</blockquote> +<p><span class="smcap">Herald, E. S.</span></p> +<blockquote> + <p>1949. Effects of DDT oil solution upon amphibians and reptiles. Herpetologica, + 5(6):117-120.</p> +</blockquote> +<p><span class="smcap">Hickman, C. P.</span></p> +<blockquote> + <p>1922. A northern record for the water moccasin. Copeia, 1922(106):39.</p> +</blockquote> +<p><span class="smcap">Hurter, J. H.</span></p> +<blockquote> + <p>1897. A contribution to the herpetology of Missouri. Trans. Acad. Sci. + St. Louis, 7:499-503.</p> +</blockquote> +<p><span class="smcap">Jacques, R.</span></p> +<blockquote> + <p>1956. The hyaluronidase content of animal venoms. Pp. 291-293 <i>in</i> Venoms (ed. Buckley, E. E., and Porges, N., Amer. Assoc. Adv. + Sci., Publ. No. 44).</p> +</blockquote> +<p><span class="pagenum"><a name="Page_488" id="Page_488">[488]</a></span></p> +<p><span class="smcap">Keegan, H. L.</span>, and <span class="smcap">Andrews, T. F.</span></p> +<blockquote> + <p>1942. Effects of crotalid venom on North American snakes. Copeia, + 1942:251-254.</p> +</blockquote> +<p><span class="smcap">Kellogg, R.</span></p> +<blockquote> + <p>1925. Poisonous snakes of the United States. U. S. D. A. Papers (371), + 13 pp.</p> +</blockquote> +<p><span class="smcap">Klauber, L. M.</span></p> +<blockquote> + <p>1941. Four papers on the application of statistical methods to herpetological + problems. Bull. Zool. Soc. San Diego, 17:1-95.</p> + <p>1956. Rattlesnakes. Univ. California Press, 2 vols., xxix + 1476 pp.</p> +</blockquote> +<p><span class="smcap">Klimstra, W. D.</span></p> +<blockquote> + <p>1959. Food habits of the cottonmouth in southern Illinois. Chicago Acad. + Sci., Nat. Hist. Misc., 168:1-8.</p> +</blockquote> +<p><span class="smcap">Laughlin, H. E.</span></p> +<blockquote> + <p>1959. Stomach contents of some aquatic snakes from Lake McAlester, + Pittsburgh County, Oklahoma. Texas Jour. Sci., 11(1):83-85.</p> +</blockquote> +<p><span class="smcap">Lederer, G.</span></p> +<blockquote> + <p>1931. Aus meinem Tagebuch. Wachenschrift fur Aquar. und Terr'kde., + 28:651-653.</p> +</blockquote> +<p><span class="smcap">Lee, H. T.</span></p> +<blockquote> + <p>1964. Letters to the Editor, Texas Game and Fish Mag., 22(3):32.</p> +</blockquote> +<p><span class="smcap">Lowe, C. H., Jr.</span></p> +<blockquote> + <p>1948. Territorial behavior in snakes and the so-called courtship dance. + Herpetologica, 4(4):129-145.</p> +</blockquote> +<p><span class="smcap">Mansueti, R.</span></p> +<blockquote> + <p>1946. Mating of the pilot blacksnake. Herpetologica, 3:98-100, 1 fig.</p> +</blockquote> +<p><span class="smcap">Martin, J. R.</span>, and <span class="smcap">Wood, J. T.</span></p> +<blockquote> + <p>1955. Notes on the poisonous snakes of the Dismal Swamp area. Herpetologica, + 11(3):237-238.</p> +</blockquote> +<p><span class="smcap">McCollough, N. C.</span>, and <span class="smcap">Gennaro, J. F., Jr.</span></p> +<blockquote> + <p>1963. Evaluation of venomous snake bite in the southern United States + from parallel clinical and laboratory investigations. Jour. Florida + Med. Assn., 49(12):959-967.</p> +</blockquote> +<p><span class="smcap">McIlhenny, E. A.</span></p> +<blockquote> + <p>1935. The alligator's life history. The Christopher Publ. House, Boston, + Massachusetts, 117 pp.</p> +</blockquote> +<p><span class="smcap">Minton, S. A., Jr.</span></p> +<blockquote> + <p>1953. Variation in venom samples from copperheads (<i>Agkistrodon contortrix + mokeson</i>) and timber rattlesnakes (<i>Crotalus horridus horridus</i>). + Copeia, 1953:212-215.</p> + <p>1954. Polyvalent antivenin in the treatment of experimental snake venom + poisoning. Amer. Jour. Trop. Med. and Hyg., 3:1077-1082.</p> + <p>1956. Some properties of North American pit viper venoms and their + correlation with phylogeny. Pp. 145-151 <i>in</i> Venoms (ed. Buckley, + E. E., and Porges, N., Amer. Assoc. Adv. Sci., Publ. No. 44).</p> +</blockquote> +<p><span class="smcap">Munro, D. F.</span></p> +<blockquote> + <p>1949. Effect of DDT powder on small cottonmouths. Herpetologica, + 5:71-72.</p> + <p>1950. Additional observations on head bobbing by snakes. Herpetologica, + 6:88.</p> +</blockquote> +<p><span class="pagenum"><a name="Page_489" id="Page_489">[489]</a></span></p> +<p><span class="smcap">Neill, W. T.</span></p> +<blockquote> + <p>1947. Size and habits of the cottonmouth moccasin. Herpetologica, + 3:203-205.</p> + <p>1949. Head bobbing, a widespread habit of snakes. Herpetologica, + 5:114-115.</p> + <p>1960. The caudal lure of various juvenile snakes. Quart. Jour. Florida + Acad. Sci., 23(3):173-200, 2 figs.</p> +</blockquote> +<p><span class="smcap">Neill, W. T.</span>, and <span class="smcap">Allen, E. R.</span></p> +<blockquote> + <p>1955. Metachrosis in snakes. Quart. Jour. Florida Acad. Sci., 18(3):207-215.</p> +</blockquote> +<p><span class="smcap">Netting, M. G.</span></p> +<blockquote> + <p>1929. The venom of <i>Sistrurus catenatus</i>. Bull. Antivenin Inst. Amer., + 2(4):108-109.</p> +</blockquote> +<p><span class="smcap">Parrish, H. M.</span></p> +<blockquote> + <p>1959. Poisonous snakebites resulting in lack of venom poisoning. Virginia + Med. Month, 86:396-401.</p> + <p>1963. Analysis of 460 fatalities from venomous animals in the United + States. Amer. Jour. Med. Sci., 245(2):35-47.</p> +</blockquote> +<p><span class="smcap">Parrish, H. M.</span>, and <span class="smcap">Pollard, C. B.</span></p> +<blockquote> + <p>1959. Effects of repeated poisonous snakebite in man. Amer. Jour. Med. + Sci., 237(3):277-286.</p> +</blockquote> +<p><span class="smcap">Penn, G. H.</span></p> +<blockquote> + <p>1943. Herpetological notes from Cameron Parish, Louisiana. Copeia, + 1943(1):58-59.</p> +</blockquote> +<p><span class="smcap">Perkins, C. B.</span></p> +<blockquote> + <p>1955. Longevity of snakes in captivity in the United States. Copeia, + 1955(3):262.</p> +</blockquote> +<p><span class="smcap">Pope, C. H.</span>, and <span class="smcap">Perkins, R. M.</span></p> +<blockquote> + <p>1944. Differences in the patterns of bites of venomous and of harmless + snakes. Archives of Surgery, 49:331-336.</p> +</blockquote> +<p><span class="smcap">Rahn, H.</span></p> +<blockquote> + <p>1942. The reproductive cycle of the prairie rattler. Copeia, 1942(4):233-240.</p> +</blockquote> +<p><span class="smcap">Ramsey, L. W.</span></p> +<blockquote> + <p>1948. Combat dance and range extension of <i>Agkistrodon piscivorus + leucostoma</i>. Herpetologica, 4:228.</p> +</blockquote> +<p><span class="smcap">Richmond, M. D.</span></p> +<blockquote> + <p>1952. Head bobbing in reptiles. Herpetologica, 8:38.</p> +</blockquote> +<p><span class="smcap">Rosenfeld, S.</span>, and <span class="smcap">Glass, S.</span></p> +<blockquote> + <p>1940. The inhibiting effect of snake bloods upon the hemorrhagic action + of viper venoms on mice. Amer. Jour. Med. Sci., 199:482-486.</p> +</blockquote> +<p><span class="smcap">Schmidt, K. P.</span></p> +<blockquote> + <p>1946. On the zoogeography of the Holarctic region. Copeia, 1946:144-152.</p> +</blockquote> +<p><span class="smcap">Shaw, C. E.</span></p> +<blockquote> + <p>1948. The male combat "dance" of some crotalid snakes. Herpetologica, + 4:137-145.</p> + <p>1951. Male combat in American colubrid snakes with remarks on combat + in other colubrid and elapid snakes. Herpetologica, 7(4):149-168.</p> +</blockquote> +<p><span class="smcap">Smith, H. M.</span></p> +<blockquote> + <p>1956. Handbook of amphibians and reptiles of Kansas. 2nd Edition. + Univ. Kansas Mus. Nat. Hist., Misc. Publ., 9:1-356, 253 figs.</p> +</blockquote> +<p><span class="pagenum"><a name="Page_490" id="Page_490">[490]</a></span></p> +<p><span class="smcap">Smith, H. M.</span>, and <span class="smcap">Buechner, H. K.</span></p> +<blockquote> + <p>1947. The influence of the Balcones Escarpment on the distribution of + amphibians and reptiles in Texas. Bull. Chicago Acad. Sci., + pp. 1-16.</p> +</blockquote> +<p><span class="smcap">Smith, P. W.</span></p> +<blockquote> + <p>1961. The amphibians and reptiles of Illinois. Illinois Nat. Hist. Survey, + 28(1):1-298.</p> +</blockquote> +<p><span class="smcap">Smith, P. W.</span>, and <span class="smcap">List, J. C.</span></p> +<blockquote> + <p>1955. Notes on Mississippi amphibians and reptiles. Amer. Midl. Nat., + 53(1):115-125.</p> +</blockquote> +<p><span class="smcap">Sowder, W. T.</span>, and <span class="smcap">Gehres, G. W.</span></p> +<blockquote> + <p>1963. Snakebites in Florida. Jour. Florida Med. Assn., 49(12):973-976.</p> +</blockquote> +<p><span class="smcap">Stabler, R. M.</span></p> +<blockquote> + <p>1951. Some observations on two cottonmouth moccasins made during 12 + and 14 years of captivity. Herpetologica, 7:89-92.</p> +</blockquote> +<p><span class="smcap">Stahnke, H. M.</span></p> +<blockquote> + <p>1953. The L-C treatment of venomous bites and stings. Amer. Jour. + Trop. Med. and Hyg., 2(1):142-143.</p> + <p>1954. The L-C method of treating venomous bites and stings. Pois. + Anim. Res. Lab., Arizona State Coll., 28 pp.</p> +</blockquote> +<p><span class="smcap">Stejneger, L.</span></p> +<blockquote> + <p>1895. The poisonous snakes of North America. Smithsonian Inst., U. S. + Nat. Mus., 1893:337-487, pls. 1-19, figs. 1-70.</p> +</blockquote> +<p><span class="smcap">Stimson, A. C.</span>, and <span class="smcap">Engelhardt, T. H.</span></p> +<blockquote> + <p>1960. The treatment of snakebite. Jour. Occ. Med., 2(4):163-168.</p> +</blockquote> +<p><span class="smcap">Sutherland, I. D.</span></p> +<blockquote> + <p>1958. The "combat dance" of the timber rattlesnake. Herpetologica, + 14(1):23-24.</p> +</blockquote> +<p><span class="smcap">Swanson, P. L.</span></p> +<blockquote> + <p>1946. Effects of snake venoms on snakes. Copeia, 1946(4):242-249.</p> +</blockquote> +<p><span class="smcap">Swaroop, S.</span>, and <span class="smcap">Grab, B.</span></p> +<blockquote> + <p>1956. The snakebite mortality problem in the world. Pp. 439-466 <i>in</i> Venoms (ed. Buckley, E. E., and Porges, N., Amer. Assoc. Adv. + Sci., Publ. No. 44).</p> +</blockquote> +<p><span class="smcap">Swartzwelder, J. C.</span></p> +<blockquote> + <p>1950. Snake-bite accidents in Louisiana with data on 306 cases. Amer. + Jour. Trop. Med., 30(4):575-589.</p> +</blockquote> +<p><span class="smcap">Tinkle, D. W.</span></p> +<blockquote> + <p>1962. Reproductive potential and cycles in female <i>Crotalus atrox</i> from + northwestern Texas. Copeia, 1962(2):306-313.</p> +</blockquote> +<p><span class="smcap">Trowbridge, A. H.</span></p> +<blockquote> + <p>1937. Ecological observations on amphibians and reptiles collected in + southeastern Oklahoma during the summer of 1934. Amer. Midl. + Nat., 18(2):285-303.</p> +</blockquote> +<p><span class="smcap">Volsøe, H.</span></p> +<blockquote> + <p>1944. Structure and seasonal variation of the male reproductive organs + in <i>Vipera berus</i> (L.). Spolia Zool. Mus. Hauniensis V. Reprint, + Copenhagen, pp. 1-172.</p> +</blockquote> +<p><span class="smcap">Wharton, C. H.</span></p> +<blockquote> + <p>1960. Birth and behavior of a brood of cottonmouths, <i>Agkistrodon piscivorus + piscivorus</i>, with notes on tail-luring. Herpetologica, 16:125-129.</p> +</blockquote> +<p><span class="pagenum"><a name="Page_491" id="Page_491">[491]</a></span></p> +<p><span class="smcap">Willson, P.</span></p> +<blockquote> + <p>1908. Snake poisoning in the United States: a study based on an + analysis of 740 cases. Arch. Int. Med., 1(5):516-570.</p> +</blockquote> +<p><span class="smcap">Wolff, N. O.</span>, and <span class="smcap">Githens, T. S.</span></p> +<blockquote> + <p>1939a. Record venom extraction from water moccasin. Copeia, 1939(1):52.</p> + <p>1939b. Yield and toxicity of venom from snakes extracted over a period of + two years. Copeia, 1939(4):234.</p> +</blockquote> +<p><span class="smcap">Wood, J. T.</span></p> +<blockquote> + <p>1954a. The distribution of poisonous snakes in Virginia. Virginia Jour. + Sci., 5(3):152-167, 4 maps.</p> + <p>1954b. A survey of 200 cases of snake-bite in Virginia. Amer. Jour. Trop. + Med. and Hyg., 3(5):936-943.</p> +</blockquote> +<p><span class="smcap">Wood, J. T.</span>, <span class="smcap">Hoback, W. W.</span>, and <span class="smcap">Green, T. W.</span></p> +<blockquote> + <p>1955. Treatment of snake venom poisoning with ACTH and cortisone. + Virginia Med. Month, 82:130-135.</p> +</blockquote> +<p><span class="smcap">Wright, A. H.</span>, and <span class="smcap">Wright, A. A.</span></p> +<blockquote> + <p>1957. Handbook of snakes of the United States and Canada. Comstock + Publ. Assoc., Cornell Univ. Press, 2:ix + 565-1106 pp.</p> +</blockquote> +<p><span class="smcap">Yamaguti, S.</span></p> +<blockquote> + <p>1958. Systema helminthum. Interscience Publ., Inc., New York, 3 vols., + 5 parts, 1:xi + 1575 pp., 2:vii + 860 pp., 3:1261 pp.</p> +</blockquote> +<p><span class="smcap">Yerger, R. W.</span></p> +<blockquote> + <p>1953. Yellow bullhead preyed upon by cottonmouth moccasin. Copeia, + 1953(2):115.</p> +</blockquote> +<p> <i>Transmitted June 20, 1966.</i></p> +<hr class="chap" /> +<p> <br /> +</p> +<h2><a name="UNIVERSITY_OF_KANSAS_PUBLICATIONS" id="UNIVERSITY_OF_KANSAS_PUBLICATIONS"></a>UNIVERSITY OF KANSAS PUBLICATIONS + MUSEUM OF NATURAL HISTORY</h2> +<p>Institutional libraries interested in publications exchange may obtain this + series by addressing the Exchange Librarian, University of Kansas Library, + Lawrence, Kansas. Copies for individuals, persons working in a particular + field of study, may be obtained by addressing instead the Museum of Natural + History, University of Kansas, Lawrence, Kansas. When copies are requested + from the Museum, 25 cents should be included (for each 100 pages or part + thereof) for the purpose of defraying the costs of wrapping and mailing. For + certain longer papers an additional amount indicated below, toward the cost + of production, is to be included. Materials published to date in this series + are as follows.</p> +<p> * An asterisk designates those numbers of which the Museum's supply (not necessarily<br /> + the Library's supply) is exhausted. Materials published to date, in this series, are as<br /> + follows:<br /> + <br /> + Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950.<br /> + <br /> + *Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp. 1-444, 140 figures in text. April 9, 1948.<br /> + <br /> + *Vol. 3. Nos. 1-4 and index. Pp. 1-681. 1951.<br /> + <br /> + *Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466, 41 plates, 31 figures in text. December 27, 1951.<br /> + <br /> + Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953.<br /> + <br /> + *Vol. 6. (Complete) Mammals of Utah, <i>taxonomy and distribution</i>. By Stephen D. Durrant. Pp. 1-549, 91 figures in text, 30 tables. August 10, 1952.<br /> + <br /> + Vol. 7. Nos. 1-15 and index. Pp. 1-651, 1952-1955.<br /> + <br /> + Vol. 8. Nos. 1-10 and index. Pp. 1-675, 1954-1956.<br /> + <br /> + Vol. 9. Nos. 1-23 and index. Pp. 1-690, 1955-1960.<br /> + <br /> + Vol. 10. Nos. 1-10 and index. Pp. 1-626, 1956-1960.<br /> + <br /> + Vol. 11. Nos. 1-10 and index. Pp. 1-703, 1958-1960.<br /> + <br /> + Vol. 12. *1. Functional morphology of three bats: Eumops, Myotis, Macrotus. By Terry<br /> + <span style="margin-left: 6em;">A. Vaughan. Pp. 1-153, 4 plates, 24 figures in text. July 8, 1959.</span><br /> + <br /> + <span style="margin-left: 3.5em;">*2. The ancestry of modern Amphibia: a review of the evidence. By Theodore</span><br /> + <span style="margin-left: 6em;">H. Eaton, Jr. Pp. 155-180, 10 figures in text. July 10, 1959.</span><br /> + <br /> + <span style="margin-left: 4em;">3. The baculum in microtine rodents. By Sydney Anderson. Pp. 181-216, 49</span><br /> + <span style="margin-left: 6em;">figures in text. February 19, 1960.</span><br /> + <br /> + <span style="margin-left: 3.5em;">*4. A new order of fishlike Amphibia from the Pennsylvanian of Kansas. By</span><br /> + <span style="margin-left: 6em;">Theodore H. Eaton, Jr., and Peggy Lou Stewart. Pp. 217-240, 12 figures in</span><br /> + <span style="margin-left: 6em;">text. May 2, 1960.</span><br /> + <br /> + <span style="margin-left: 4em;">5. Natural history of the Bell Vireo. By Jon C. Barlow. Pp. 241-296, 6 figures</span><br /> + <span style="margin-left: 6em;">in text. March 7, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">6. Two new pelycosaurs from the lower Permian of Oklahoma. By Richard C.</span><br /> + <span style="margin-left: 6em;">Fox. Pp. 297-307, 6 figures in text. May 21, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">7. Vertebrates from the barrier island of Tamaulipas, México. By Robert K.</span><br /> + <span style="margin-left: 6em;">Selander, Richard F. Johnston, B. J. Wilks, and Gerald G. Raun. Pp. 309-345,</span><br /> + <span style="margin-left: 6em;">plates 5-8. June 18, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">8. Teeth of edestid sharks. By Theodore H. Eaton, Jr. Pp. 347-362, 10 figures</span><br /> + <span style="margin-left: 6em;">in text. October 1, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">9. Variation in the muscles and nerves of the leg in two genera of grouse</span><br /> + <span style="margin-left: 6em;">(Tympanuchus and Pedioecetes). By E. Bruce Holmes. Pp. 363-474, 20</span><br /> + <span style="margin-left: 6em;">figures. October 25, 1962. $1.00.</span><br /> + <br /> + <span style="margin-left: 3.5em;">10. A new genus of Pennsylvanian fish (Crossopterygii, Coelacanthiformes) from</span><br /> + <span style="margin-left: 6em;">Kansas. By Joan Echols. Pp. 475-501, 7 figures. October 25, 1963.</span><br /> + <br /> + <span style="margin-left: 3.5em;">11. Observations on the Mississippi Kite in southwestern Kansas. By Henry S.</span><br /> + <span style="margin-left: 6em;">Fitch. Pp. 503-519. October 25, 1963.</span><br /> + <br /> + <span style="margin-left: 3.5em;">12. Jaw musculature of the Mourning and White-winged doves. By Robert L.</span><br /> + <span style="margin-left: 6em;">Merz. Pp. 521-551, 22 figures. October 25, 1963.</span><br /> + <br /> + <span style="margin-left: 3.5em;">13. Thoracic and coracoid arteries in two families of birds, Columbidae and</span><br /> + <span style="margin-left: 6em;">Hirundinidae. By Marion Anne Jenkinson. Pp. 553-573, 7 figures. March</span><br /> + <span style="margin-left: 6em;">2, 1964.</span><br /> + <br /> + <span style="margin-left: 3.5em;">14. The breeding birds of Kansas. By Richard F. Johnston. Pp. 575-655, 10</span><br /> + <span style="margin-left: 6em;">figures. May 18, 1964. 75 cents.</span><br /> + <br /> + <span style="margin-left: 3.5em;">15. The adductor muscles of the jaw in some primitive reptiles. By Richard C.</span><br /> + <span style="margin-left: 6em;">Fox. Pp. 657-680, 11 figures in text. May 18, 1964.</span><br /> + <br /> + <span style="margin-left: 3.5em;">Index. Pp. 681-694.</span><br /> + <br /> + Vol. 13. 1. Five natural hybrid combinations in minnows (Cyprinidae). By Frank B.<br /> + <span style="margin-left: 6em;">Cross and W. L. Minckley. Pp. 1-18. June 1, 1960.</span><br /> + <br /> + <span style="margin-left: 4em;">2. A distributional study of the amphibians of the Isthmus of Tehuantepec,</span><br /> + <span style="margin-left: 6em;">México. By William E. Duellman. Pp. 19-72, plates 1-8, 3 figures in text.</span><br /> + <span style="margin-left: 6em;">August 16, 1960. 50 cents.</span><br /> + <br /> + <span style="margin-left: 4em;">3. A new subspecies of the slider turtle (Pseudemys scripta) from Coahuila,</span><br /> + <span style="margin-left: 6em;">México. By John M. Legler. Pp. 73-84, plates 9-12, 3 figures in text.</span><br /> + <span style="margin-left: 6em;">August 16, 1960.</span><br /> + <br /> + <span style="margin-left: 3.5em;">*4. Autecology of the copperhead. By Henry S. Fitch. Pp. 85-288, plates 13-20,</span><br /> + <span style="margin-left: 6em;">26 figures in text. November 30, 1960.</span><br /> + <br /> + <span style="margin-left: 4em;">5. Occurrence of the garter snake, Thamnophis sirtalis, in the Great Plains and</span><br /> + <span style="margin-left: 6em;">Rocky Mountains. By Henry S. Fitch and T. Paul Maslin. Pp. 289-308,</span><br /> + <span style="margin-left: 6em;">4 figures in text. February 10, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">6. Fishes of the Wakarusa River in Kansas. By James E. Deacon and Artie L.</span><br /> + <span style="margin-left: 6em;">Metcalf. Pp. 309-322, 1 figure in text. February 10, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">7. Geographic variation in the North American cyprinid fish, Hybopsis gracilis.</span><br /> + <span style="margin-left: 6em;">By Leonard J. Olund and Frank B. Cross. Pp. 323-348, plates 21-24, 2</span><br /> + <span style="margin-left: 6em;">figures in text. February 10, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">8. Descriptions of two species of frogs, genus Ptychohyla; studies of American</span><br /> + <span style="margin-left: 6em;">hylid frogs, V. By William E. Duellman. Pp. 349-357, plate 25, 2</span><br /> + <span style="margin-left: 6em;">figures in text. April 27, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">9. Fish populations, following a drought, in the Neosho and Marais des Cygnes</span><br /> + <span style="margin-left: 6em;">rivers of Kansas. By James Everett Deacon. Pp. 359-427, plates 26-30,</span><br /> + <span style="margin-left: 6em;">3 figures. August 11, 1961. 75 cents.</span><br /> + <br /> + <span style="margin-left: 3.5em;">10. Recent soft-shelled turtles of North America (family Trionychidae). By</span><br /> + <span style="margin-left: 6em;">Robert G. Webb. Pp. 429-611, plates 31-54, 24 figures in text. February</span><br /> + <span style="margin-left: 6em;">16, 1962. $2.00.</span><br /> + <br /> + <span style="margin-left: 4em;">Index. Pp. 613-624.</span><br /> + <br /> + Vol. 14. 1. Neotropical bats from western México. By Sydney Anderson. Pp. 1-8.<br /> + <span style="margin-left: 6em;">October 24, 1960.</span><br /> + <br /> + <span style="margin-left: 4em;">2. Geographic variation in the harvest mouse, Reithrodontomys megalotis, on</span><br /> + <span style="margin-left: 6em;">the central Great Plains and in adjacent regions. By J. Knox Jones, Jr.,</span><br /> + <span style="margin-left: 6em;">and B. Mursaloglu. Pp. 9-27, 1 figure in text. July 24, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">3. Mammals of Mesa Verde National Pork, Colorado. By Sydney Anderson.</span><br /> + <span style="margin-left: 6em;">Pp. 29-67, plates 1 and 2, 3 figures in text. July 24, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">4. A new subspecies of the black myotis (bat) from eastern Mexico. By E.</span><br /> + <span style="margin-left: 6em;">Raymond Hall and Ticul Alvarez. Pp. 69-72, 1 figure in text. December</span><br /> + <span style="margin-left: 6em;">29, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">5. North American yellow bats, "Dasypterus," and a list of the named kinds</span><br /> + <span style="margin-left: 6em;">of the genus Lasiurus Gray. By E. Raymond Hall and J. Knox Jones, Jr.</span><br /> + <span style="margin-left: 6em;">Pp. 73-98, 4 figures in text. December 29, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">6. Natural history of the brush mouse (Peromyscus boylii) in Kansas with</span><br /> + <span style="margin-left: 6em;">description of a new subspecies. By Charles A. Long. Pp. 99-111, 1 figure</span><br /> + <span style="margin-left: 6em;">in text. December 29, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">7. Taxonomic status of some mice of the Peromyscus boylii group in eastern</span><br /> + <span style="margin-left: 6em;">Mexico, with description of a new subspecies. By Ticul Alvarez. Pp. 113-120,</span><br /> + <span style="margin-left: 6em;">1 figure in text. December 29, 1961.</span><br /> + <br /> + <span style="margin-left: 4em;">8. A new subspecies of ground squirrel (Spermophilus spilosoma) from Tamaulipas,</span><br /> + <span style="margin-left: 6em;">Mexico. By Ticul Alvarez. Pp. 121-124. March 7, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">9. Taxonomic status of the free-tailed bat, Tadarida yucatanica Miller. By J.</span><br /> + <span style="margin-left: 6em;">Knox Jones, Jr., and Ticul Alvarez. Pp. 125-133, 1 figure in text. March 7,</span><br /> + <span style="margin-left: 6em;">1962.</span><br /> + <br /> + <span style="margin-left: 3.5em;">10. A new doglike carnivore, genus Cynaretus, from the Clarendonian Pliocene,</span><br /> + <span style="margin-left: 6em;">of Texas. By E. Raymond Hall and Walter W. Dalquest. Pp. 135-138,</span><br /> + <span style="margin-left: 6em;">2 figures in text. April 30, 1962.</span><br /> + <br /> + <span style="margin-left: 3.5em;">11. A new subspecies of wood rat (Neotoma) from northeastern Mexico. By</span><br /> + <span style="margin-left: 6em;">Ticul Alvarez. Pp. 139-143, April 30, 1962.</span><br /> + <br /> + <span style="margin-left: 3.5em;">12. Noteworthy mammals from Sinaloa, Mexico. By J. Knox Jones, Jr., Ticul</span><br /> + <span style="margin-left: 6em;">Alvarez, and M. Raymond Lee. Pp. 145-159. 1 figure in text. May 18,</span><br /> + <span style="margin-left: 6em;">1962.</span><br /> + <br /> + <span style="margin-left: 3.5em;">13. A new bat (Myotis) from Mexico. By E. Raymond Hall. Pp. 161-164,</span><br /> + <span style="margin-left: 6em;">1 figure in text. May 21, 1962.</span><br /> + <br /> + <span style="margin-left: 3em;">*14. The mammals of Veracruz. By E. Raymond Hall and Walter W. Dalquest.</span><br /> + <span style="margin-left: 6em;">Pp. 165-362, 2 figures. May 20, 1963. $2.00.</span><br /> + <br /> + <span style="margin-left: 3.5em;">15. The recent mammals of Tamaulipas, México. By Ticul Alvarez. Pp. 363-473,</span><br /> + <span style="margin-left: 6em;">5 figures in text. May 20, 1963. $1.00.</span><br /> + <br /> + <span style="margin-left: 3.5em;">16. A new subspecies of the fruit-eating bat, Sturnira ludovici, from western</span><br /> + <span style="margin-left: 6em;">Mexico. By J. Knox Jones, Jr., and Gary L. Phillips. Pp. 475-481, 1 figure</span><br /> + <span style="margin-left: 6em;">in text. March 2, 1964.</span><br /> + <br /> + <span style="margin-left: 3.5em;">17. Records of the fossil mammal Sinclairella, Family Apatemyidae, from the</span><br /> + <span style="margin-left: 6em;">Chadronian and Orellan. By William A. Clemens. Pp. 483-491. 2 figures</span><br /> + <span style="margin-left: 6em;">in text. March 2, 1964.</span><br /> + <br /> + <span style="margin-left: 3.5em;">18. The mammals of Wyoming. By Charles A. Long. Pp. 493-758, 82 figs.</span><br /> + <span style="margin-left: 6em;">July 6, 1965. $3.00.</span><br /> + <br /> + <span style="margin-left: 3.5em;">Index. Pp. 759-784.</span><br /> + <br /> + Vol. 15. 1. The amphibians and reptiles of Michoacán, México. By William E. Duellman.<br /> + <span style="margin-left: 6em;">Pp. 1-148, plates 1-6, 11 figures in text. December 20, 1961. $1.50.</span><br /> + <br /> + <span style="margin-left: 4em;">2. Some reptiles and amphibians from Korea. By Robert G. Webb, J. Knox</span><br /> + <span style="margin-left: 6em;">Jones, Jr., and George W. Byers. Pp. 149-173. January 31, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">3. A new species of frog (Genus Tomodactylus) from western México. By</span><br /> + <span style="margin-left: 6em;">Robert G. Webb. Pp. 175-181, 1 figure in text. March 7, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">4. Type specimens of amphibians and reptiles in the Museum of Natural History,</span><br /> + <span style="margin-left: 6em;">the University of Kansas. By William E. Duellman and Barbara Berg.</span><br /> + <span style="margin-left: 6em;">Pp. 183-204. October 26, 1962.</span><br /> + <br /> + <span style="margin-left: 4em;">5. Amphibians and Reptiles of the Rainforests of Southern El Petén, Guatemala.</span><br /> + <span style="margin-left: 6em;">By William E. Duellman. Pp. 205-249, plates 7-10, 6 figures in text. October</span><br /> + <span style="margin-left: 6em;">4, 1963.</span><br /> + <br /> + <span style="margin-left: 4em;">6. A revision of snakes of the genus Conophis (Family Colubridae, from Middle</span><br /> + <span style="margin-left: 6em;">America). By John Wellman. Pp. 251-295, 9 figures in text. October 4,</span><br /> + <span style="margin-left: 6em;">1963.</span><br /> + <br /> + <span style="margin-left: 4em;">7. A review of the Middle American tree frogs of the genus Ptychohyla. By</span><br /> + <span style="margin-left: 6em;">William E. Duellman. Pp. 297-349, plates 11-18, 7 figures in text. October</span><br /> + <span style="margin-left: 6em;">18, 1963. 50 cents.</span><br /> + <br /> + <span style="margin-left: 3.5em;">*8. Natural history of the racer Coluber constrictor. By Henry S. Fitch. Pp.</span><br /> + <span style="margin-left: 6em;">351-468, plates 19-22, 20 figures in text. December 30, 1963. $1.00.</span><br /> + <br /> + <span style="margin-left: 3.5em;">9. A review of the frogs of the Hyla bistincta group. By William E. Duellman.</span><br /> + <span style="margin-left: 6em;">Pp. 469-491, 4 figures in text. March 2, 1964.</span><br /> + <br /> + <span style="margin-left: 3.5em;">10. An ecological study of the garter snake, Thamnophis sirtalis. By Henry S.</span><br /> + <span style="margin-left: 6em;">Fitch. Pp. 493-564, plates 23-25, 14 figures in text. May 17, 1965.</span><br /> + <br /> + <span style="margin-left: 3.5em;">11. Breeding cycle in the ground skink, Lygosoma laterale. By Henry S. Fitch</span><br /> + <span style="margin-left: 6em;">and Harry W. Greene. Pp. 565-575, 3 figures in text. May 17, 1965.</span><br /> + <br /> + <span style="margin-left: 3.5em;">12. Amphibians and reptiles from the Yucatan Peninsula, México. By William</span><br /> + <span style="margin-left: 6em;">E. Duellman. Pp. 577-614, 1 figure in text. June 22, 1965.</span><br /> + <br /> + <span style="margin-left: 3.5em;">13. A new species of turtle, Genus Kinosternon, from Central America, by John</span><br /> + <span style="margin-left: 6em;">M. Legler. Pp. 615-625, pls. 26-28, 2 figures in text. July 20, 1965.</span><br /> + <br /> + <span style="margin-left: 3.5em;">14. A biogeographic account of the herpetofauna of Michoacán, México. By</span><br /> + <span style="margin-left: 6em;">William E. Duellman. Pp. 627-709, pls. 29-36, 5 figures in text. December</span><br /> + <span style="margin-left: 6em;">30, 1965.</span><br /> + <br /> + <span style="margin-left: 3.5em;">15. Amphibians and reptiles of Mesa Verde National Park, Colorado. By Charles</span><br /> + <span style="margin-left: 6em;">L. Douglas. Pp. 711-744, pls. 37, 38, 6 figures in text. March 7, 1966.</span><br /> + <br /> + <span style="margin-left: 3.5em;">Index. Pp. 745-770.</span><br /> + <br /> + Vol. 16. 1. Distribution and taxonomy of Mammals of Nebraska. By J. Knox Jones, Jr.<br /> + <span style="margin-left: 6em;">Pp. 1-356, pls. 1-4, 82 figures in text. October 1, 1964. $3.50.</span><br /> + <br /> + <span style="margin-left: 4em;">2. Synopsis of the lagomorphs and rodents of Korea. By J. Knox Jones, Jr.,</span><br /> + <span style="margin-left: 6em;">and David H. Johnson. Pp. 357-407. February 12, 1965.</span><br /> + <br /> + <span style="margin-left: 4em;">3. Mammals from Isla Cozumel, Mexico, with description of a new species of</span><br /> + <span style="margin-left: 6em;">harvest mouse. By J. Knox Jones, Jr., and Timothy E. Lawlor. Pp. 409-419,</span><br /> + <span style="margin-left: 6em;">1 figure in text. April 13, 1965.</span><br /> + <br /> + <span style="margin-left: 4em;">4. The Yucatan deer mouse, Peromyscus yucatanicus. By Timothy E. Lawlor.</span><br /> + <span style="margin-left: 6em;">Pp. 421-438, 2 figures in text. July 20, 1965.</span><br /> + <br /> + <span style="margin-left: 4em;">5. Bats from Guatemala. By J. Knox Jones, Jr. Pp. 439-472. April 18, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">More numbers will appear in volume 16.</span><br /> + <br /> + Vol. 17. 1. Localities of fossil vertebrates obtained from the Niobrara Formation (Cretaceous)<br /> + <span style="margin-left: 6em;">of Kansas. By David Bardack. Pp. 1-14. January 22, 1965.</span><br /> + <br /> + <span style="margin-left: 4em;">2. Chorda tympani branch of the facial nerve in the middle ear of tetrapods.</span><br /> + <span style="margin-left: 6em;">By Richard C. Fox. Pp. 15-21, May 22, 1965.</span><br /> + <br /> + <span style="margin-left: 4em;">3. Fishes of the Kansas River System in relation to zoogeography of the Great</span><br /> + <span style="margin-left: 6em;">Plains. By Artie L. Metcalf. Pp. 23-189, 4 figures in text, 51 maps.</span><br /> + <span style="margin-left: 6em;">March 24, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">4. Factors affecting growth and reproduction of channel catfish, Ictalurus punctatus.</span><br /> + <span style="margin-left: 6em;">By Bill A. Simco and Frank B. Cross. Pp. 191-256, 13 figures in</span><br /> + <span style="margin-left: 6em;">text. June 6, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">5. A new species of fringe-limbed tree frog, genus Hyla, from Darién, Panamá.</span><br /> + <span style="margin-left: 6em;">By William E. Duellman. Pp. 257-262, 1 figure in text. June 17, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">6. Taxonomic notes on some Mexican and Central American hylid frogs. By</span><br /> + <span style="margin-left: 6em;">William E. Duellman. Pp. 263-279. June 17, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">7. Neotropical hylid frogs, genus Smilisca. By William E. Duellman and</span><br /> + <span style="margin-left: 6em;">Linda Trueb. Pp. 281-375, pls. 1-12, 17 figures in text. July 14, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">8. Birds from North Borneo. By Max C. Thompson. Pp. 377-433, 1 figure in</span><br /> + <span style="margin-left: 6em;">text. October 27, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">9. Natural history of cottonmouth moccasin, Agkistrodon piscivorus (Reptilia).</span><br /> + <span style="margin-left: 6em;">By Ray D. Burkett. Pp. 435-491, 7 figures in text. October 27, 1966.</span><br /> + <br /> + <span style="margin-left: 4em;">More numbers will appear in volume 17.</span><br /> +</p> + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of Natural History of Cottonmouth +Moccasin, Agkistrodon piscovor, by Ray D. 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