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diff --git a/36286-8.txt b/36286-8.txt new file mode 100644 index 0000000..ea682d9 --- /dev/null +++ b/36286-8.txt @@ -0,0 +1,1674 @@ +The Project Gutenberg EBook of Natural History of the Prairie Vole +(Mammalian Genus Microtus), by E. W. Jameson + +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 the Prairie Vole (Mammalian Genus Microtus) + [KU. Vol. 1 No. 7] + +Author: E. W. Jameson + +Editor: E. Raymond Hall + Donald S. Farner + H. H. Lane + Edward H. Taylor + +Release Date: May 30, 2011 [EBook #36286] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK PRAIRIE VOLE (MAMMALIAN GENUS MICROTUS) *** + + + + +Produced by Chris Curnow, Joseph Cooper, Diane Monico, and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + + + + + + +NATURAL HISTORY OF THE +PRAIRIE VOLE + +(~Mammalian Genus~ Microtus) + +BY + +E. W. JAMESON, Jr. + + +University of Kansas Publications +Museum of Natural History + +Volume 1, No. 7, pp. 125-151 +October 6, 1947 + + +UNIVERSITY OF KANSAS +LAWRENCE +1947 + + + + +UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY + +Editors: E. Raymond Hall, Chairman; Donald S. Farner, H. H. Lane, +Edward H. Taylor + +Volume 1, No. 7, pp. 125-151 +October 6, 1947 + + +UNIVERSITY OF KANSAS +Lawrence, Kansas + + +PRINTED BY +FERD VOILAND, JR., STATE PRINTER +TOPEKA, KANSAS +1947 + +21-6957 + + + + +NATURAL HISTORY OF THE PRAIRIE VOLE +(MAMMALIAN GENUS MICROTUS) + +By +E. W. JAMESON, JR. + + + + +CONTENTS + + + PAGE + +Introduction 128 + +Methods 130 + +Molt 131 + +Food and Habitat 132 + Types of cover 132 + Cuttings 133 + Food caches 134 + Plants used as food and as cover 135 + +Associates 137 + +Nest and Burrows 137 + +External Parasites 138 + Fleas (Siphonaptera) 139 + Lice (Anoplura) 141 + Mites (Acari except Ixodoidea) 142 + Ticks (Ixodoidea) 143 + +Reproduction 144 + Age classes 144 + Fecundity 144 + Size of litters 146 + The breeding season 147 + +Summary 149 + +Literature Cited 150 + + + + +INTRODUCTION + + +The prairie vole (_Microtus ochrogaster_) at Lawrence, Kansas, is +approximately 5-1/2 inches in length, of which the tail comprises 1-1/4 +inches, and weighs approximately 1-1/2 ounces. The color on the dorsum +is dark gray with a grizzled appearance from the mixture of black and +fulvous on the long hairs; the venter is paler, sometimes pale fulvous +or cinnamon. The animal is compactly built much as are the other +microtine rodents. The short legs and short tail, small eyes and partly +hidden ears, and heavy and flattened head all suggest its semifossorial +mode of life. The prairie vole spends most of its time in an elaborate +system of tunnels (some entirely below the ground) and in almost hidden +galleries in the dense grass. + +_Microtus ochrogaster_ can be separated from other voles in its +geographic range by a combination of several characters. The plantar +tubercles usually number five, although a few individuals with six +tubercles were found at Lawrence, Kansas. _Microtus pennsylvanicus_, +normally with six plantar tubercles, as Bole and Moulthrop (1942:156) +pointed out, sometimes has only five. Therefore, the number of plantar +tubercles alone is not a certain means for separating _pennsylvanicus_ +from _ochrogaster_. The color of the venter of _ochrogaster_ is usually +fulvous or cinnamon instead of grayish as in _pennsylvanicus_, but there +is variation in this respect too; some prairie voles also have a grayish +venter. The shorter tail of _ochrogaster_ will assist in establishing +its identity where it occurs with _pennsylvanicus_. The third upper +molar has two closed triangles in _ochrogaster_ and usually three in +_pennsylvanicus_. The pelage of _ochrogaster_ is coarse whereas +_pennsylvanicus_ has fine fur. Prairie voles may be separated from pine +mice (_Pitymys nemoralis_ and _P. pinetorum_) with which they are +sometimes found, by the larger eyes, less rusty color, and longer tail. +The Cooper lemming mouse (_Synaptomys cooperi_) differs from the prairie +vole in having the upper incisors grooved, and in possessing a shorter +tail which approximates the hind foot in length. + +Of _Microtus ochrogaster_ from Lawrence, Douglas County, Kansas, average +measurements of twenty-five adult males are: total length, 143 (121-167) +mm.; tail, 32 (25-42) mm.; hind feet, 20 (17-22) mm.; weight, 43 (38-55) +grams. Twenty-five adult females from the same place average: total +length, 150 (131-170) mm.; tail, 33 (31-41) mm.; hind foot, 19 (17-21) +mm.; weight, 45 (38-58) grams. + +The prairie vole is found in suitable habitats in the central part of +North America. It has been recorded from Edmonton, Alberta, in the +northwest (Bailey, 1900:76), southeastward to Chesapeake, Ohio (Bole and +Moulthrop, _op. cit._:156), and in the southwest as far as Ft. Reno, +Oklahoma (Bailey, _op. cit._:74). See figure 1 showing the known range +of _Microtus ochrogaster_. _Microtus ludovicianus_, a close relative of +_ochrogaster_, has been taken along the southern part of the boundary +between Texas and Louisiana (Lowery, 1943:247). + +The activities of voles, especially those of the genus _Microtus_, +attracted the attention of naturalists even in early times. Aristotle +(translated by Thompson, 1910) wrote: "The rate of propagation of field +mice in country places, and the destruction that they cause, are all +beyond telling. In many places their number is so incalculable that but +very little of the corn-crop is left to the farmer; and so rapid is +their mode of proceeding that sometimes a small farmer will one day +observe that it is time for reaping, and on the following morning, when +he takes his reapers afield, he finds his entire crop devoured. Their +disappearance is unaccountable: in a few days not a mouse will be there +to be seen." + +[Illustration: FIGURE 1. Range of the Prairie Vole (_Microtus +ochrogaster_).] + +Several early naturalists in this country commented on the fluctuations +in numbers of individuals, and on the breeding and feeding habits of +voles. Kennicott (1857) in an agricultural report on the mammals of +Illinois wrote about the breeding of the prairie vole. He described its +stores of plants and commented on the behavior of some captives. Quick +and Butler (1885) discussed the habits of _Microtus ochrogaster_ as +well as those of _M. pennsylvanicus_, _Pitymys pinetorum_, and +_Synaptomys cooperi_ in Indiana, and described the feeding and breeding +habits of these species. Criddle (1926) gave an account of the feeding +and breeding habits of _Microtus ochrogaster_ in Manitoba, and Fisher +(1945) published a short description of the food and reproduction of the +same species as he observed it in Missouri. Stone investigated the fauna +in the nests of this vole in the same state, but has not yet, as of +March, 1946, published his findings. + + + + +METHODS + + +The information in the present account was obtained by observing animals +in the field, and by examining trapped animals that were brought into +the laboratory. Five hundred individuals were caught in snap-traps, and +forty additional voles that were marked were captured a total of 157 +times. More than 90 per cent of the specimens were trapped at Lawrence, +Douglas County, Kansas, but voles were examined also in Ellsworth, +Atchison, and Jefferson counties, Kansas, and in Douglas County, +Illinois. My data pertain to _Microtus ochrogaster_ in the above named +areas from October, 1945, until August, 1946. The findings may not be +typical of this species in other areas and in other years. + +The museum special traps were used both with and without bait. The bait +consisted of a piece of walnut meat on the treadle. By placing the trap +crosswise in the runway, voles were captured whether or not the treadle +was baited. Immediately upon removal from the trap, each vole was placed +in a white flannel sack, one sack sufficing for several voles when +necessary. In this way the loss of ectoparasites was kept to a minimum. +The fleas were counted, and the numbers of lice and mites were +estimated; some specimens of ectoparasites were saved for +identification. + +The voles taken in live traps were marked and released. The marking was +done by cutting off one or more toes in such a manner that the vole +could later be identified. From left to right, the toes were assigned +numbers from one to five on the left hind foot, and by tens from ten to +fifty on the right hind foot. Number 33, therefore, was assigned to the +one vole of which the middle toe of each hind foot had been cut off. +Each time an animal was captured alive, it was weighed, specimens of +fleas, lice and mites were preserved, and the external appearance of the +reproductive organs was noted. The extent of the molt line, if the vole +was molting, was recorded. Corresponding data were kept for each dead +vole caught in a snap trap. + +Assistance is acknowledged from Professors E. Raymond Hall, A. Byron +Leonard, Worthie H. Horr, and Donald F. Hoffmeister; and I have had also +much helpful advice from Professors W. J. Hamilton, Jr., and P. C. +Stone. + + + + +MOLT + + +The skins of 44 molting prairie voles were pinned out flat. The flesh +sides clearly show the areas of molt. Various stages in the molt process +were observed also in animals caught in live traps. The molt begins when +the animal is three or four weeks old; at this time the juvenal pelage +is replaced by the subadult pelage. The second molt occurs when the +prairie vole is between eight and twelve weeks old, and is the means by +which the adult pelage replaces the subadult pelage. These same two +molts were found by Hatfield (1935) to occur in captive _Microtus +californicus_. Molting voles of the species ochrogaster were trapped in +each month of the year. + +The molting processes of juveniles and subadults follow the same +pattern. The first area of molting is in the pectoral region. The molt +patch extends caudad toward the tail and cephalad toward the chin. New +pelage separates this area of active molt into two strips on the fourth +or fifth day. By this time each strip has spread laterad to the legs and +sides, and is 10 to 20 mm. wide. Ultimately each strip unites with its +opposite, usually at the center of the dorsum. This area of molt then +spreads cephalad and caudad. Fourteen to fifteen days after the +beginning of the molt, the entire dorsum is in process of being covered +with new pelage. Shortly before the completion of the molt, the dorsal +area of molt divides into two patches, one on the rump and one on the +nape. The areas last to be covered with new pelage are the crown and +that between the ears and the eyes. A slight variation in the above +process occurred in some specimens in which the lateral strips joined +immediately cephalad of the tail instead of at the center of the dorsum. +The entire process takes approximately three weeks. + +Large voles (45 grams or more) grow hair in irregular patches that +measured 5 to 15 mm. In these large voles the molt is accomplished +slowly and does not cover large areas of the body at any one time. The +small areas of molt are visible for 7 to 10 days, and were found on +approximately three quarters of the large voles examined. + + + + +FOOD AND HABITAT + + +The diet of the prairie vole reflects both its environment and its +choice of food. The plants eaten are usually green and succulent, but +some dry, hard seeds and small stems of woody plants are also eaten. The +vegetation, which supplies the food for the vole, is important as cover +or nesting material. For this reason food and habitat are discussed +together. + + +TYPES OF COVER + +Prairie voles inhabit areas where the dominant plants in summer are +clover or grasses or both. The lawn on the campus at the University of +Kansas consists mostly of several kinds of grasses, but in some places +alfalfa (_Medicago sativa_) replaces clover (_Trifolium_ sp.), and in +other places sedges (_Scirpus_ spp.) are found in addition to the +grasses. The grass is short; it is mowed to a length of 4 to 6 inches. +Bluegrass (_Poa pratensis_) and crabgrass (_Digitaria ischaemum_) form +most of the sod. Bluejoint (_Andropogon furcatus_) is common in a +sparsely wooded part of the campus, an area which has many voles. +Foxtail (_Setaria lutescens_ and _S. viridis_) and prairie threeawn +(_Aristida oligantha_) are also common on the lawn, but these become dry +in late summer, and at that time supply neither food nor cover for the +voles. The voles make well-beaten depressions in the sod, and the grass +arches over them to form canopies. + +In the winter, when the snow flattened the grass on the campus so that +there were no longer protective canopies of blades over the runways of +the voles, they migrated into areas of Japanese honeysuckle (_Lonicera +japonica_). At this season the honeysuckle was their main food. In areas +where this vine was not available, the voles abandoned their surface +runways and remained below the ground, coming to the surface only under +the protection of a blanket of snow. The voles returned to the grass and +clover habitat in March and April in 1946. + +One pure stand of Ladino clover in Jefferson County, Kansas, was studied +in late November and early December of 1945. The clover was 2 to 4 +inches high, and although it was the sole food of the voles, it +furnishes but little cover. They were common here; 300 traps yielded 111 +voles in two nights. + + +CUTTINGS + +The voles seek particularly the tender heads of grasses and the terminal +leaves of sweet clover (_Melilotus alba_). To obtain these parts, the +voles begin by cutting through the base of the plant. The surrounding +plants are often near enough to support the freshly cut piece in an +upright position. The vole makes successive cuttings, 40 or 50 +millimeters from the ground, until the desired parts of the plant are +within reach. The cuttings that have accumulated at the base of the +plant may be eaten, but frequently they remain as evidence of the vole's +feeding activity. + +On May 12, 1946, an analysis was made of the cuttings found in an area +of alfalfa, grasses, and weeds. From table 1 it may be seen that +quackgrass, alfalfa, wild lettuce, and cleavers were common. In three +nights 70 traps caught 8 prairie voles and 3 deer mice; no pine mice or +cotton rats were caught on the area. The stomachs of the voles and the +deer mice were examined, and only the stomachs of the voles contained +green material. Analysis of the cuttings (see table 2) indicates that +alfalfa was eaten in greater quantity than any other plant; it made up +almost three quarters of the cuttings although but one quarter of the +cover. All other plants occurred less commonly in the piles of cuttings +than they did in the estimated composition of the cover. Grasses and +wild lettuce were next to alfalfa in importance. + +TABLE 1.--_The Relative Abundance of Plants in an Area of Alfalfa, +Grasses, and Weeds_[A] + + Percentage by number + Species of plants + +Quackgrass (_Agropyron repens_) 30 +Speargrass (_Poa annua_) 1 +California brome (_Bromus carinatus_) 1 +Smooth brome (_Bromus inermis_) 1 +Alfalfa (_Medicago sativa_) 25 +Peppergrass (_Lepidium densiflorum_) 2 +Cleavers (_Galium aparine_) 15 +Wild lettuce (_Lactuca scariola_) 25 + +TABLE 2.--_Composition of Ten Piles of Cuttings_[B] + + Frequency of + Species Ten piles of cuttings occurrence + +_Agropyron repens_ 1 0 0 2 0 0 6 19 0 4 13 +_Poa annua_ 0 0 0 0 0 0 0 0 0 0 00 +_Bromus carinatus_ 0 0 0 0 0 10 0 0 0 0 04 +_Bromus inermis_ 0 0 0 0 0 0 0 0 0 0 00 +_Medicago sativa_ 40 14 30 30 31 5 0 0 21 4 73 +_Lepidium densiflorum_ 0 0 0 0 0 0 0 0 0 0 00 +_Galium aparine_ 0 0 0 0 1 0 1 0 0 0 01 +_Lactuca scariola_ 6 2 1 2 5 0 0 0 2 4 09 + +[Footnote A: Analysis made on May 12, 1946, on an area 20 × 80 yards, at +Lawrence, Kansas.] + +[Footnote B: Each of the first ten vertical columns gives the +composition of one pile of cuttings. The last column gives the +percentage of occurrence in the piles of cuttings of each species of +plant in the area. Place and date for data in table 2 same as for table +1.] + +Approximately one out of every ten voles caught in snap traps had a +piece of plant in its mouth. Occasionally a vole took a piece of food +into a live trap. Evidently the food is not always eaten where it is +procured. Grasses of the genus _Poa_ are the kinds most frequently found +in the mouths of dead voles. _Bromus carinatus_, _B. inermis_ and sweet +clover (_Melilotus alba_) were found in the runways. The pulpy fruit of +the horse nettle (_Solanum carolinense_) was found partly eaten, +especially near the entrances to underground passages. + + +FOOD CACHES + +Caches of seeds and underground parts of plants are stored in +subterranean chambers. One lot of food was found stored on the surface +of the ground. Four times, piles of seeds in runways indicated the +species of plants which the voles were storing. + +One underground cache was found on May 27, 1946, on the University +campus, by John Evans, Richard Edgar, and the writer. This cache was in +a large chamber in a tunnel system of the prairie vole, on an +east-facing hillside of walnut trees, catalpas, and Kentucky coffee +trees. The oval chamber was 250 mm. wide, 400 mm. long, and 200 mm. +high. The roof, at its highest point, was 30 mm. below the surface of +the ground. There were two entrances to the cavity, both on the downhill +side. The cache consisted of eight quarts of seeds (approximately 2,800) +of the Kentucky coffee tree (_Gymnocladus dioica_). The seeds were +packed with earth and all were well preserved. The site of this cache +was in an area which was shaded by a small coffee tree. A seed of this +tree is spheroidal, measures 17 mm. in width, and weighs 2 grams. + +Several times in the fall of 1945, in the above-mentioned grove, the +writer found pods of the coffee tree lying in the runs of the voles. +These pods were sometimes entire, but more often they had been gnawed; +frequently only part of a pod remained, indicating that the voles were +storing or feeding upon the seeds, although the possibility that the +mice were storing food did not occur to the writer at the time. Three +times, seeds of other plants were found piled at the entrances of the +burrows of voles. Twice these piles consisted of from 50 to 70 seeds of +the common dandelion (_Taraxacum officinale_). The third pile was +composed of 20 seeds of the giant ragweed (_Ambrosia trifida_). + +A pasture of Canadian bluegrass (_Poa compressa_), wild millet +(_Echinochloa crusgalli_), sedges (_Scirpus_ spp.), and clover +(_Trifolium_ sp.) in Atchison County, Kansas, was examined in November, +1945. This area was the home of a dense population of prairie voles. +Wherever a path of the voles crossed a deep imprint of a horse's hoof, +there was a collection of cuttings from the horizontal stems of the +clover which bordered the runways. Some of the cuttings may have been +made by lemming mice (_Synaptomys cooperi_) which were also common in +the area. + +Several kinds of voles store food. Bailey (1920) wrote of the caches of +_Microtus pennsylvanicus_ in North Dakota, where, in one locality, this +vole was known as the bean mouse. He stated that the Indians dug up +beans (_Falcata comosa_) and the tubers of the Jerusalem artichoke +(_Helianthus tuberosus_) which the voles had stored. Lantz (1907:17) +found a cache of the roots of wild morning glory (_Convolvulus sepium_) +laid away by _Microtus pennsylvanicus_. Nelson (1893:140) wrote that, as +winter approached, _Microtus operarius_ gathered small bulbous roots, +sometimes storing a peck or more in a single cavity. Fisher (1945) in +Missouri found a gallon of the fruits of the horse nettle (_Solanum +carolinense_) stored in a hollow stump by the prairie vole. Kennicott +(1857:99) found five or six quarts of roots of two species of +spike-flower (_Liatrus_), _Helianthus_, and various grasses among the +winter provisions of the prairie vole in Illinois. + + +PLANTS USED AS FOOD AND AS COVER + +Table 3 lists, according to their families, the species of plants which +the prairie vole was observed to use for food. The same species are +sometimes used as cover. The majority of the plants are in three +families: the grass family (Graminae), the pulse family (Leguminosae), +and the composite family (Compositae). + +The grasses that supply the voles' food and cover are mostly _Poa_ (the +bluegrasses) and _Bromus_ (bromegrass, chess, or cheat). _Poa pratensis_ +is a common lawn and pasture grass, _P. annua_ is a weed species. The +bluegrasses begin to grow in late winter about Lawrence, Kansas, and +they remain green until late in the fall. During this time, the voles +eat the blades and heads of bluegrass, and make their runways under the +culms. The prairie voles utilize several species of _Bromus_. _Bromus +inermis_ and _B. carinatus_ are important range and pasture grasses, but +_japonicus_ is a weed of little or no economic value. These are soft, +tender grasses, but, in contrast to the bluegrasses, they become dry in +midsummer, and are then unsuitable as food. However, they continue to +form a protection over the runways of the voles. + +The legumes, which appeared to be most important to the prairie vole, +are clover (_Trifolium_ spp. and _Melilotus alba_) and alfalfa +(_Medicago sativa_). These plants are common in both cultivated and +feral states. They form a different type of cover from that made by +grasses. Voles, living in clover and alfalfa, do not make runways as +distinct as they do in grasslands. The clover and alfalfa plants are +branched and of a spreading growth form, whereas the grasses have leaves +which are appressed to the main stem. The individual grass plants grow +close together, and a vole cannot run through grass without trampling +some of it. As voles use the same paths repeatedly, the grass in their +runs becomes flattened and dies. There is sufficient room between the +stems of the clover and alfalfa plants to allow the voles to pass +through without treading on the stems. In such a habitat, vole runways +are poorly developed, and are difficult to find. Voles in grasslands +feed in runways, as attested by the piles of cuttings found in the +runways and the nibbled grass which borders them. Voles in clover or +alfalfa feed at the bases of the plants wherever the plants may grow. In +the latter type of cover the cuttings are rather evenly distributed. + +Compositae formed a minor part of the cover in most of the habitats +studied. Many grasslands have a stand of dandelions; sow thistle, wild +lettuce, and ragweed were also common in some grasslands. The voles ate +the leaves and sometimes the seeds and underground parts of these +plants. + +TABLE 3. _Plants Used for Food by the Prairie Vole_ + +Graminae + _Poa annua_ + _P. compressa_ + _P. pratensis_ + _Bromus inermis_ + _B. carinatus_ + _B. japonicus_ + _Andropogon furcatus_ + _Agropyron repens_ + _Setaria lutescens_ + _S. viridis_ + +Leguminosae + _Melilotus alba_ + _Medicago sativa_ + _Trifolium_ spp. + _Gymnocladus dioica_ + +Solanaceae + _Solanum carolinense_ + +Boraginaceae + _Galium aparine_ + +Caprifoliaceae + _Lonicera japonica_ + +Compositae + _Lactuca scariola_ + _Sonchus arvensis_ + _Ambrosia trifida_ + _A. artemisiifolia_ + _Taraxacum officinale_ + + + + +ASSOCIATES + + +In the mixed areas of grassland and clover that were described above, +the cotton rat (_Sigmodon hispidus_), the deer mouse (_Peromyscus +maniculatus_), and the little short-tailed shrew (_Cryptotis parva_) +were commonly caught in the runways of the prairie vole. Less frequently +trapped were the common mole (_Scalopus aquaticus_), the large +short-tailed shrew (_Blarina brevicauda_), the Cooper lemming mouse +(_Synaptomys cooperi_), the pine mouse (_Pitymys nemoralis_), and the +harvest mouse (_Reithrodontomys megalotis_). In the dense growth of +Japanese honeysuckle, the prairie vole shared runways with the +white-footed mouse (_Peromyscus leucopus_), the large short-tailed +shrew, and the pine mouse. + + + + +NEST AND BURROWS + + +The prairie vole makes a tortuous network of paths through the grass and +honeycombs the topsoil with its tunnels. The underground passages lead +to nests or to chambers where food is sometimes stored. The runways +through the grass are 40 to 50 mm. wide, and usually lie slightly below +the surface of the ground. By using the same path repeatedly, the voles +create little ruts in which they run. The bottom of the runways are bare +soil or are covered with only a thin layer of trampled grass. Cotton +rats, on the other hand, apparently do not use their runs over long +periods, for they are not well-beaten runways, but are made merely by +parting the grass and not by trampling it down or cutting it off. Voles +were trapped in runways of the cotton rats, but no cotton rat was caught +in a typical runway of a vole. + +The burrows of the prairie vole are 40 to 50 mm. in diameter, and the +shallowest part is usually 50 to 100 mm. below the surface of the +ground. Burrows leading to nests or food chambers may descend deeper +than the others. Some prairie voles were trapped in tunnels of the +common mole (_Scalopus aquaticus_). The voles make their own burrows, +and are especially active at this task when a hard rain has loosened the +previously hard, dry soil. The rain in the first two weeks of October, +1945, made the soil much more friable than it had been at the beginning +of the month, and the voles took advantage of the favorable opportunity +to construct many new burrows. In October, particles of soil were packed +beneath the toenails of many specimens. + +In this time fifteen nests were found. They were 6 to 18 inches below +the surface of the ground, and two tunnels led from each nest to the +surface runway. The nest cavities were spheroidal, and measured 150 to +200 mm. horizontally, and 80 to 100 mm. vertically. The floors were +slightly concave and were covered with loose dirt and a mixture of dried +grass and one or two leaves. The remainder of the cavity was filled with +the dry grass of which the nest was composed. Criddle (1926) stated that +at Treesbank, Manitoba, this vole makes its nests in the burrow systems +of the pocket gopher (_Thomomys talpoides_); and Kennicott (1857:98) +found nests of the prairie vole in old ant hills. + +Each of two nests that had been recently occupied was placed in a +Berlese funnel, and in this way the arthropod fauna of the nests was +collected. The most common arthropods in the nests were mites +(parasitic, predaceous, and free-living) and springtails. Sowbugs, +centipedes, spiders, and fleas were also present. Of these arthropods, +the laelaptid mites, one kind of tick, and one kind of flea have a +direct relationship with the vole. These parasites are the same species +which are found on the vole itself. The mites were _Eulaelaps +stabularis_ (Koch) and _Atricholaelaps glasgowi_ (Ewing). One adult +tick, _Ixodes sculptus_ Newman, was in one nest. The fleas, about a +dozen in each nest, were _Ctenophthalmus pseudagyrtes_ Baker, the flea +most frequently found on the prairie vole. + + + + +EXTERNAL PARASITES + + +The pelage of prairie voles, pine mice, deer mice, and shrews forms a +habitat for many kinds of parasitic arthropods. The fleas, lice, and +mites from the prairie vole were collected, counted, and identified. The +ectoparasites from the other small mammals living in the same habitat as +the prairie vole were also considered. Some ectoparasites begin to leave +the host when it dies, and any counts of ectoparasites made from +snap-trapped voles may fall short of the number which was on the animal +when it was alive. The average number of fleas recorded from live voles +exceeds that found on snap-trapped voles (see table 4). The numbers of +lice and mites were estimated, but selected voles were examined to +obtain absolute numbers of these kinds of ectoparasites. + +The fleas, lice, and mites were mounted on one inch by three inch glass +slides; the ticks were preserved in 70 per cent alcohol. Dr. E. W. Baker +identified the mites; Dr. R. A. Cooley and Dr. Glen M. Kohls, the ticks; +Dr. G. W. Wharton, the chiggers; and Dr. Gordon F. Ferris, the lice. To +each of these gentlemen I am grateful. The fleas were identified by +myself. + + +FLEAS (SIPHONAPTERA) + +The information on the average numbers of fleas on voles was obtained +from live-trapped and some snap-trapped voles. Fleas were counted only +on voles which were removed from the traps within twenty-four hours +after the traps had been last examined. The average numbers of fleas +found on prairie voles in this study are given in table 4. + +TABLE 4. _Average Numbers of Fleas on Prairie Voles_[C] + + Subadults Adults + +Live-trapped voles 1.9 (73) 3.4 (29) +Snap-trapped voles 1.1 (26) 1.3 (27) + +[Footnote C: The fleas on the live-trapped voles are all _Ctenophthalmus +pseudagyrtes_ Baker, and those on snap-trapped voles represent several +species (see table 2). The numbers in parentheses are the numbers of +voles examined.] + +Table 5 shows the average degree of infestation for ten months of an +eleven month period. The monthly averages for the most part show no +variations. The latter half of February provides an exception in that a +series of 22 snap-trapped voles and 11 live-trapped voles taken at that +time had on the average, 9.7 and 5.3 fleas respectively. Pine mice +(_Pitymys nemoralis_) occurred in small numbers in the area where +_Microtus ochrogaster_ was live-trapped, and _Ctenophthalmus +pseudagyrtes_ was the flea found to be common on both of these voles. + +TABLE 5.--_Monthly Averages of Fleas on Prairie Voles_ + +Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. + + .6 5.1 5[D] ... 3 1.8 1.4 1.7 ... 1.1 2 2 + (6) (11) (6) ... (6) (88) (26) (6) ... (8) (14) (2) + +[Footnote D: This figure is high because one vole had the high number of +19 fleas. The numbers in parentheses show the number of live voles +examined for each month. All fleas were _Ctenophthalmus pseudagyrtes_ +Baker.] + +Some fleas have a habitat preference as well as a host specificity. As +voles from different areas were examined, different kinds of fleas were +encountered. A population of free-living voles under observation on the +Campus at Lawrence was parasitized only by _Ctenophthalmus +pseudagyrtes_. From 90 prairie voles collected in a field of clover 4 +miles northwest of Lawrence, the only species of flea recovered was +_Orchopeas leucopus_. In both places the prairie vole was the most +common mammal, but in the field of clover three deer mice (_P. +maniculatus_) also were trapped. In a third field, one mile west of +Lawrence, the prairie vole was host to both the above mentioned fleas. +Here both the prairie vole and the cotton rat (_Sigmodon hispidus_) were +common. + +The host distribution of fleas on seven small mammals which lived in the +same habitats as the prairie vole is given in table 6. + +TABLE 6.--_Frequency of Occurrence of Fleas on Seven Species of Small +Mammals_[E] + +Column headings: + +A: _Cryptotis parva_ +B: _Blarina brevicauda_ +C: _Peromyscus maniculatus_ +D: _Peromyscus leucopus_ +E: _Sigmodon hispidus_ +F: _Microtus ochrogaster_ +G: _Pitymys nemoralis_ + + A B C D E F G +---------------------------------------------------------------- +_Orchopeas leucopus_ (Baker) 0 0 53 31 37 6 10 +_Orchopeas howardii_ (Baker) = + _O. wickhami_ (Baker) 0 0 0 0 0 1 0 +_Nosopsyllus fasciatus_ (Bosc) 0 0 0 0 0 1 0 +_Epitedia wenmanni_ (Rothschild) 0 0 0 9 0 2 0 +_Rectofrontia fraterna_ (Baker) 0 0 0 0 0 1 0 +_Corrodopsylla hamiltoni_ (Traub) 47 8 0 0 0 0 0 +_Ctenophthalmus pseudagyrtes_ Baker 0 38 0 0 4 25 53 +_Peromyscopsylla scotti_ I. Fox 0 0 0 6 0 0 0 + -------------------------- + Total number examined 34 13 34 35 57 414 21 +---------------------------------------------------------------- + +[Footnote E: The numbers represent the percentage of each species which +was parasitized by fleas. The mammals were collected at Lawrence, +Douglas County, Kansas, between October, 1945, and June, 1946. These +data are entirely from snap-trapped animals with the exception of those +from _Microtus_ and _Pitymys_ which are from both snap-trapped and +live-trapped animals.] + +It is seen that some fleas are rather specific in their choice of hosts, +and that others are commonly found on two or more small mammals in the +same habitat. In each of these groups there are fleas which have a +habitat preference, that is to say, the flea lives on the host when the +host lives in a given habitat, but is absent when the host lives in +another habitat. + + +GROUP 1: FLEAS WITH A HOST PREFERENCE + +_Epitedia wenmanni_ was found on the white-footed mouse (_Peromyscus +leucopus_) and only rarely on the prairie vole. _Corrodopsylla +hamiltoni_ was taken only from the two kinds of shrews (_Blarina +brevicauda_ and _Cryptotis parva_). Fleas on shrews may have a +well-developed host preference. At any rate, Elton, Baker, Ford, and +Gardner (1931) found that _Doratopsylla dasycnemus_ rarely strayed from +its normal host (_Sorex araneus_) to other small mammals. +_Peromyscopsylla scotti_ was taken from the white-footed mouse +(_Peromyscus leucopus_), and had a habitat preference also. It was found +only on those white-footed mice which were trapped in the woodlands at +various places in Douglas County; white-footed mice which were trapped +in areas of brush were free of this parasite. + + +GROUP 2: FLEAS COMMONLY FOUND ON TWO OR MORE KINDS OF SMALL MAMMALS + +_Orchopeas leucopus_ was an outstanding example of this group. It was +the most common flea on the deer mouse, the white-footed mouse, and the +cotton rat. In certain areas it was common on the two voles (_Pitymys +nemoralis_ and _Microtus ochrogaster_). _Ctenophthalmus pseudagyrtes_ is +the most abundant flea on the two kinds of voles and on the large shrew +(_Blarina brevicauda_), and was found sparingly on the cotton rat. + +Several kinds of fleas do not belong in either of the above groups. Some +fleas were accidental strays from mammals not included in table 6; and +one flea (_Rectofrontia fraterna_) may prove to be a common nest +parasite. _Orchopeas howardii_ is common on tree squirrels (_Sciurus +niger_ and _S. carolinensis_). _Nosopsyllus fasciatus_ is a cosmopolitan +flea on _Rattus norvegicus_. _Rectofrontia fraterna_ was taken once from +a prairie vole. Since the only specimens in the University of Kansas +Entomological Collections are from "mouse nests," this flea may be found +to be a nest inhabiting parasite. + +Some fleas are possible bridges by which a blood parasite could be +transmitted from one kind of a mammal to another. If _Ctenophthalmus +pseudagyrtes_ acted as the intermediate host of a disease-causing +organism, an epizootic from _Microtus ochrogaster_ might be transmitted +to _Pitymys nemoralis_ or to _Sigmodon hispidus_ or _Blarina +brevicauda_. There are several other such potential bridges for blood +parasites. Although table 6 does not prove that individual fleas wander +from one host to another, the frequency with which the several kinds of +fleas are removed from live mice suggests that the fleas occasionally do +so. + + +LICE (ANOPLURA) + +Lice collected from the prairie vole were all of one species, +_Hoplopleura acanthopus_ (Burmeister). Of 59 voles examined for the +presence of lice, 33 were found to be parasitized; the 59 voles had an +average of 3.4 lice each. Other mice which used the same runways as the +prairie vole had their own species of Anoplura. The cotton rat was host +to _Hoplopleura hirsuta_ Ferris, and the two species of _Peromyscus_ +were parasitized by _Hoplopleura hesperomydis_ (Osborn). + +The writer collected _Hoplopleura acanthopus_ from _Microtus +californicus_ at Calaveras Dam, Alameda County, California, and from _M. +pennsylvanicus_ at Ithaca, Tompkins County, New York. Elton, Ford, +Baker, and Gardner (1931) recorded this same species from _M. argestis_ +in England. + +Lice on the prairie vole are the same species as those found on other +species of _Microtus_ in other areas, but since Anoplura of the prairie +vole do not parasitize the cotton rat, the white-footed mouse, and the +deer mouse, this host specificity of lice makes it unlikely that lice +would carry blood parasites from the prairie vole to any of the latter +named rodents. + + +MITES (ACARINA EXCEPT IXODOIDEA) + +Many of the small mammals examined in this study had mites, some of +which were collected and identified. Mites were collected from other +species of voles in several localities in the United States and in one +locality in Canada; as voles in widely separated regions are sometimes +hosts to the same species of mites, these records will be presented +here. + +The frequency of some kinds of mites in the identified material suggests +that they are more abundant than other kinds. The occurrence of mites on +small mammals from Lawrence, Kansas, is presented in table 7. + +The following comments can be made concerning the specificity and +geographic ranges of several species of mites: + +_Liponyssus occidentalis_ Ewing was found only on _Cryptotis parva_. + +_Eulaelaps stabularis_ (Koch) was one of the more common kinds found on +the prairie vole. This mite is rather large (about 1 mm. long) and is +frequently (with the following species) seen running through the pelage +of its host. In addition to the records for this species in table 1, it +was found to be a common parasite on _Pitymys pinetorum_ at Point Abino, +Welland County, Ontario. Elton, Ford, Baker and Gardner (1931) found +this same mite on _Apodemus sylvaticus_ and _Clethrionomys glareolus_ in +England. + +_Atricholaelaps glasgowi_, like the preceding species, was one of the +commoner mites on the prairie vole. It was found also on _Pitymys +pinetorum_ at Point Abino, Welland County, Ontario; on _Microtus +pennsylvanicus_ at Ithaca, Tompkins County, New York; and on _M. +californicus_ at Calaveras Dam, Alameda County, California. + +_Atricholaelaps sigmodoni_ occurred only on the cotton rat. + +_Laelaps kochi_ was less commonly found than _Eulaelaps stabularis_ and +_Atricholaelaps glasgowi_. In Kansas the prairie vole and the cotton rat +were hosts to _Laelaps kochi_, and it occurred on _Microtus +pennsylvanicus_ at Ithaca, New York, and on _M. californicus_ at +Berkeley, California. + +Trombiculidae are commonly known by their larvae which are called +chiggers or harvest mites. The white-footed mouse, the cotton rat, and +the prairie vole were parasitized at Lawrence. In the winter these mites +live in the ears of these small mammals, but in the summer they were +found both in the ears and on the rump. Those obtained in winter were +_Ascoschöngastia brevipes_ (Ewing); other species may be involved. + +Listrophoridae was represented on the prairie vole by a species of +_Myocoptes_ and a species of _Listrophorus_. These mites cling to the +hairs of their host, and do not occur on the skin of the voles. + +No evidence was seen that mites had any ill effect on the health of +their hosts. No voles had scabs on the skin; and the ears were not +swollen and disfigured as they sometimes are by chiggers. Although the +identity of a specimen of mite could not be determined until it was +mounted, a person could tell whether or not it was one of the larger, +very active Laelaptidae, one of the hair-clinging Listrophoridae, or one +of the tiny, orange Trombiculidae. + +On July 12, 1946, three prairie voles were examined to determine the +number of mites they supported. The voles were freshly caught, no one of +them having been dead for more than five minutes before they were +examined. These three voles had an average of 25 Laelaptidae, 22 +Listrophoridae, and 53 Trombiculidae. + +Six species of mites (Ixodoidea excepted) were found on the prairie +vole. Four of these were collected also from other small mammals living +in the same habitat as this vole. Two species of mites were found to +occur on voles in New York, Kansas, and California. + + +TICKS (IXODOIDEA) + +Two kinds of ticks were found. One adult specimen of _Ixodes sculptus_ +Neumann was clinging to the head of a vole, just in front of its eye. +This species of tick was taken also from the thirteen-lined ground +squirrel (_Citellus tridecimlineatus_) at Lawrence. One nymph of +_Dermacentor variabilis_ (Say) was found attached to the scapular region +of a prairie vole. Both of these specimens were taken in June. + +TABLE 7. _Host Distribution of Mites on Seven Small Mammals_[F] + +Column headings: + +A: _Scalopus aquaticus_ +B: _Cryptotis parva_ +C: _Blarina brevicauda_ +D: _Peromyscus maniculatus_ +E: _Peromyscus leucopus_ +F: _Sigmodon hispidus_ +G: _Microtus ochrogaster_ + + A B C D E F G +------------------------------------------------------------------------- +_Ascoschöngastia brevipes_ (Ewing) .. .. .. .. X X X +_Liponyssus occidentalis_ Ewing .. X .. .. .. .. .. +_Eulaelaps stabularis_ (Koch) X X X .. X .. X +_Atricholaelaps glasgowi_ (Ewing) .. .. .. X .. .. X +_Atricholaelaps sigmodoni_ Strandtmann .. .. .. .. .. X .. +_Laelaps kochi_ Oudemans .. .. .. .. .. X X +_Myocoptes_ sp. .. .. .. .. .. .. X +_Listrophorus_ sp. .. .. .. .. .. .. X +------------------------------------------------------------------------- + +[Footnote F: These data are from material collected at Lawrence, Douglas +County, Kansas.] + + + + +REPRODUCTION + + +AGE CLASSES + +Each prairie vole was assigned to one of three age classes (juvenile, +subadult, or adult) principally on the basis of weight, but partly on +the quality and color of the pelage. The three age classes are +characterized in table 8. + +TABLE 8. _Characters of Juvenile, Subadult, and Adult Prairie Voles_ + + Juvenile Subadult Adult + +Less than 21 grams 21-38 grams 38 grams or more + +Weight usually less Average weight Average weight +than 20 grams 30-32 grams 40-45 grams + +Entire pelage dull Pelage of rump Pelage usually + dull; rest of entirely glossy + pelage glossy (rump sometimes dull) + +Dorsal color black Dorsal color Entire dorsal color + grizzled except grizzled except + on rump sometimes on rump + + +FECUNDITY + +Hamilton (1941:4) found for _Microtus pennsylvanicus_ that macroscopic +tubules of the cauda epididymis were an indication of fecundity. By +noting the size of the tubules (whether macroscopic or not) and by +making smears from them in approximately every 25th male caught, I found +that the presence of sperm was positively correlated with large-sized +tubules of the cauda epididymis in _Microtus ochrogaster_. +Inferentially, males with sperm were fecund. + +There is a relationship almost positive between the size of the tubules +of the cauda epididymis and the length of the testes. Testes longer +than 7 mm. have macroscopic tubules in the cauda, and in testes shorter +than 7 mm. these tubules cannot be seen with the naked eye, Hamilton +(1937b) found that in _M. pennsylvanicus_ testes smaller than 8 × 4 mm. +did not contain sperm. The testes of the prairie vole descend into the +scrotum in the breeding season. In the two winter months, when the voles +did not bring forth young, the testes decreased in size (see figure 3) +and were withdrawn into the body cavity. The presence of the testes in +the body cavity does not mean that a vole is not in breeding condition, +for many specimens with abdominal testes were fecund. + +The females were considered to be fecund if they were gravid, or if +there were placental scars in the horns of the uteri. + +[Illustration: FIGURE 2. Fecundity of Prairie Voles by Months. Adults +and Subadults are Considered Together.] + +[Illustration: FIGURE 3. Seasonal Changes in the Length of Testes.] + + +SIZE OF LITTERS + +The number of mammae characteristic of a species of vole may be a rough +guide to the average size of a litter for that species. The prairie vole +has fewer mammae (three pairs) than some other voles in North America, +and might, therefore, be expected to have smaller litters. Fifty-eight +gravid females of _Microtus ochrogaster_ examined by me had an average +of 3.4 embryos each; the number of embryos ranged from one to seven. +Hamilton (1936a) gave 5.07 as the average number of young per litter in +_M. pennsylvanicus_. Hatfield (1935) stated that _M. californicus_ has +an average of 5.7 young in a litter. Both _pennsylvanicus_ and +_californicus_ normally have four pairs of mammae. The expectation as to +the size of the litter seems to be realized. In the prairie vole one +pair of mammae is pectoral and two pairs are abdominal. Usually a +lactating vole showed evidence of only the abdominal mammae having been +in use. + +The size of litters was found to vary with the season of the year (see +table 9). Gravid females were collected in every breeding month except +September. + +TABLE 9. _Average Size of Litters of Microtus ochrogaster by Months_[G] + +Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. + + 0 2.8 3.9 3.2 3.4 3.1 2.8 3.0 .. 3.2 2.6 0 + .. (4) (10) (6) (8) (9) (5) (2) .. (5) (5) .. + +[Footnote G: These months are from October, 1945, until August, 1946. +The numbers in parentheses indicate the number of gravid females +collected each month.] + +Table 9 shows that the prairie vole produced the largest litters in +March. A comparison of table 9 with figure 2 shows that the largest +litters were produced at the height of the breeding season. Baker and +Ransom (1933), studying _Microtus agrestis_, also found that larger +litters were characteristic of the height of the breeding season; and +that at the beginning and at the end of the breeding season the litters +averaged smaller. + +The size of litters varied also with the age of the female. To place a +gravid female in its proper age class, the weight of the embryos was +subtracted from the total weight, and the remaining weight was used as +the body weight. The average size of the litters of 14 subadults was +2.9, and in 35 adults it was 3.4. Hatfield (_op. cit._) found that the +younger females of _M. californicus_ gave birth to smaller litters than +did the adults. + +Not included in either of the above analyses are nine gravid females +collected in November in a pasture watered by an artesian spring in +Atchison County, Kansas. In this pasture there was a high concentration +of prairie voles, and the percentage of fecundity was much higher than +in Douglas County at the same time. In November only 29 per cent of the +female prairie voles in Douglas County were fecund, as against 59 per +cent in Atchison County. The average number of embryos of these nine +voles was 4.1. Data from Atchison County are not included in table 9. + + +THE BREEDING SEASON + +In October, 1945, when this study was begun, the prairie vole was +bringing forth young. In the winter of 1945-'46 at Lawrence, Kansas, +there was a cessation of reproduction. The reproductive activity was +measured in terms of the fecundity of the subadults and the adults of +both sexes. Figure 2 suggests that the decline was most marked in +December and January; no gravid females were collected in these two +months, although two females trapped in the first week of December were +lactating. In October, November, and December, 85 per cent of the +breeding females were adults. In October, 85 per cent of the adult +females were fecund, and in November, this figure was 80 per cent. +Reproduction at this season, in the females, it appears, was largely a +function of the adults. The proportion of adults to the rest of the +population was calculated for each month; and the monthly changes in +relative numbers of adults is shown in figure 4. In November, December, +and January there was a scarcity of adult voles in the population. The +autumnal decline in reproduction occurred simultaneously with the +disappearance of these adults, and is thought to have been largely a +result of it. + +Reproductive activity began in February; and in this month one-third of +the females contained embryos, and 90 per cent of the males were fecund. +Reproduction reached its height in March when fecundity for the females +and males was 77 per cent and 100 per cent respectively. In April both +sexes showed signs of being less productive, and still later in the +spring the percentage of fecundity remained at slightly over 65 for both +sexes, this figure being higher for the males than for the females for +any one month. From January to February there was a 30 per cent increase +in the percentage of adults in the population; and for this period, +there was a 33 per cent increase in the fecundity of both males and +females. In February, 80 per cent of the fecund females were adults. The +breeding in the late winter, as in the fall, is thought to depend upon +the percentage of adults in the population. Hamilton (1937b) noted a +similar correlation between winter breeding and dominance of adults in +_Microtus pennsylvanicus_ in New York. Fisher (1945) found that the +prairie vole continued to breed throughout the winter of 1943-'44 in +Missouri; in such a case, one would expect to find a large proportion of +adults in the population. + +[Illustration: FIGURE 4. Seasonal Changes in the Numbers of Adults in +Relation to the Total Population of Prairie Voles.] + +Throughout the winter of 1945-'46, at Lawrence, the majority of males +were fecund; but fecundity in the females was much less, and in January, +no females showed signs of reproductive activity. From this it appears +that the females, not the males, limit the breeding season of this +species. + + + + +SUMMARY + + +In the eleven month period, October, 1945, until August, 1946, in +northeastern Kansas, more than five hundred specimens of the prairie +vole (_Microtus ochrogaster_) were examined in the flesh; and forty +free-living voles were examined 157 times--an average of slightly less +than four times each. + +There is a complete molt from juvenal to subadult pelage, and one from +subadult to adult pelage. These molts require three weeks each. +Subsequent molts are irregular and extend over longer periods of time. + +This vole, in summer, inhabits areas of grass, clover, and alfalfa. In +winter, habitats with some woody growth may be sought. Twenty-two kinds +of plants were found to be used for food. Although most of these were +succulent plants, seeds and small woody stems were sometimes eaten. The +prairie vole, like some other species of _Microtus_, lays away stores of +food, usually underground; the maximum quantity found in one cache was +two gallons. + +Nine other species of small mammals occur in the same habitat with the +prairie vole, and frequently use its runways. The vole makes a network +of paths through the grass, and constructs its own burrows which lead to +its nests and food stores. Each of fifteen nests found were underground. +Most, if not all, of the underground tunnels are dug when the soil is +moist, not when the soil is dry. + +The commonest flea on the prairie vole is _Ctenophthalmus pseudagyrtes_; +it averages 1.9 (for subadult voles) to 3.4 (for adult voles) per +individual vole. Other fleas on this vole are _Orchopeas leucopus_, +_Orchopeas howardii_, _Nosopsyllus fasciatus_, _Epitedia wenmanni_, and +_Rectofrontia fraterna_. The two species of fleas which were actually +common on the vole (_C. pseudagyrtes_ and _O. leucopus_), parasitized +also some other small mammals which lived in the same habitat as the +vole. One species of sucking louse (_Hoplopleura acanthopus_) and two +kinds of mites (_Laelaps kochi_ and _Atricholaelaps glasgowi_) which +occur on the prairie vole in Kansas, occur also on _Microtus +californicus_ in California and on _M. pennsylvanicus_ in New York. Only +three ticks (1 _Dermacenter variabilis_ and 2 _Ixodes sculptus_) were +found on the prairie vole. + +Fifty-eight gravid females had an average of 3.4 embryos. Litters at the +height of the breeding season are larger than those at the beginning and +at the end of the breeding season. Reproduction in _Microtus +ochrogaster_ ceased in December, 1945, in northeastern Kansas, and the +first evidence of reproduction in 1946 was observed in February. + + + + +LITERATURE CITED + + +BAILEY, V. + + 1900. Revision of the American voles of the genus Microtus. N. + Amer. Fauna, 17:1-88, June 6, 1900. + + 1920. Identity of the bean mouse of Lewis and Clark. Jour. Mamm., + 1:70-72, November 28, 1919. + +BAKER, J. R., and RANSOM, R. M. + + 1933. Factors affecting the breeding of the field mouse (_Microtus + agrestris_). Part 11. Temperature and food. Royal Soc. London + Proc., (Ser. B) 112:39-46, November 1, 1932. + +BOLE, B. P., JR., and MOULTHROP, P. N. + + 1942. The Ohio Recent mammal collection in the Cleveland Museum + of Natural History. Sci. Pub. Cleveland Mus. Nat. Hist., + 6:83-181, September 11, 1942. + +CRIDDLE, S. + + 1926. Habits of Microtus minor in Manitoba. Jour. Mamm., 7:193-200, + August 9, 1926. + +ELTON, C. S., E. B. FORD, J. R. BAKER, and A. D. GARDNER. + + 1931. The health and parasites of a wild mouse population. Proc. + Zoöl. Soc. London, 101:657-721, September 30, 1931. + +FISHER, H. J. + + 1945. Notes on voles in central Missouri. Jour. Mamm., 26:435-437, + November, 1945. + +HATFIELD, D. M. + + 1935. A natural history study of Microtus californicus. Jour. + Mamm., 16:261-271, November 15, 1935. + +HAMILTON, W. J., JR. + + 1937a. The biology of microtine cycles. Jour. Agr. Res., + 54:779-790, May 15, 1937. + + 1937b. Growth and life span of the field mouse. American Nat., + 71:500, September-October, 1937. + + 1941. The reproduction of the field mouse, Microtus pennsylvanicus + (Ord). Cornell Univ. Agr. Exp. Sta. Memoir 237, pp. 1-23, + May, 1941. + +KENNICOTT, R. + + 1856. The quadrupeds of Illinois. Part I, Rep. Commiss. Patents: + Agriculture, pp. 52-110, 1857. + +LANTZ, D. E. + + 1907. An economic study of field mice (genus _Microtus_). U.S.D.A. + Bull. Biol. Surv., 31:1-64, October 28, 1907. + +LOWERY, G. H., JR. + + 1943. Check-list of the mammals of Louisiana and adjacent waters. + Occas. Papers Mus. Zoöl., Louisiana State Univ., 13:213-257, + November 22, 1943. + +NELSON, E. W. + + 1893. Description of a new species of _Arvicola_, of the Mynomes + group, from Alaska. Proc. Biol. Soc. Washington, 8:140-142, + December 28, 1893. + +QUICK, E. W., and A. W. BUTLER. + + 1885. The habits of some Arvicolinae. American Nat., 19:113-118, + February, 1885. + +_Transmitted August 13, 1946._ + +21-6957 + + + + + * * * * * + +Transcriber's Notes + + +Italic text is shown within _underscores_. + +Bold text is shown within ~tildes~. + +Page 136, Table 3, under Compositae: changed Loctuca to Lactuca + (_Loctuca scariola_) + + and changed artemsiifolia to artemisiifolia + (_A. artemsiifolia_) + +Page 139: changed trappd to trapped + (from live-trapped and some snap-trappd voles.) + + and changed rate to rat + (the prairie vole and the cotton rate) + +Page 141: changed Almeda to Alameda + (at Calaveras Dam, Almeda County, California,) + +Page 142: kept section heading: Mites (Acarina except Ixodoidea) + (the TOC lists the variation Acari instead of Acarina) + + and changed Almeda to Alameda + (at Calaveras Dam, Almeda County, California.) + +Page 143: changed tridecimlineaus to tridecimlineatus + (ground squirrel (_Citellus tridecimlineaus_) at Lawrence.) + Note: Another spelling variation is: tridecemlineatus. + +Page 146: changed table 2 to table 9 + (A comparison of table 2 with figure 2 shows that the largest) + +Page 143: kept spelling variation: Dermacentor variabilis + +Page 149: kept spelling variation: Dermacenter variabilis + +Page 150: changed LITERAURE to LITERATURE + (LITERAURE CITED) + + and kept spelling variation: agrestris, being a reference citation + (1933. Factors affecting ... field mouse (_Microtus agrestris_)). + + + + + + + + +End of the Project Gutenberg EBook of Natural History of the Prairie Vole +(Mammalian Genus Microtus), by E. W. Jameson + +*** END OF THIS PROJECT GUTENBERG EBOOK PRAIRIE VOLE (MAMMALIAN GENUS MICROTUS) *** + +***** This file should be named 36286-8.txt or 36286-8.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/3/6/2/8/36286/ + +Produced by Chris Curnow, Joseph Cooper, Diane Monico, and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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