James R. Beer

Hibernation of the Big Brown Bat

Relatively few of the some 1300 species of bats live in the temperate regions of the world. Many of the species found in this northern region live through the winter by hibernating. But hibernating bats, in contrast to other hibernating mammals such as the hedgehog and ground squirrels, are essentially poikilothermous (Kayser, 1940). Their metabolism is proportional to their body temperature, and in the inactive state they show no evidence of a thermoregulatory mechanism (Hock, 1951). Hence in bats there appears to be no real distinction between sleep and hibernation. The state of hibernation for bats can be defined, then, only as a relatively long period or series of periods when the animals are subjected to low environmental temperatures, become inactive, and have a very low metabolic rate correlated with a low body temperature. There is some disagreement in the literature as to the requirements for successful hibernation in bats. Rysgaard (1942), for instance, felt that in the more northern areas it was necessary for bats to carry out a limited amount of feeding during hibernation, while Bailey (1928) was of the opinion that bats not only do not feed but that they remain motionless during the entire period. Observations by Guthrie (1933) and others agree with our observation that bats move periodically during hibernation, as demonstrated by the subsequent locations found occupied by banded specimens (Beer, 1955). However, activity during winter months does not necessarily imply that the active bats are able to find food during a Minnesota winter (in some of the caves they could obtain water to drink). This suggestion that activity does not necessarily imply feeding is supported by the fact that we have held big brown bats in the cold (4–5°C) in laboratory cages from the middle of November after they had been in …

Survival and Movements of Banded Big Brown Bats

Between 1932 and 1951, over 67,000 bats have been banded in North America (Mohr, 1952). This gives some idea as to the lack of data for any given species since there are some 36 species of bats found in the United States. The number of big brown bats banded has not been large. The literature based on these banding data contains some instructive information as well as some controversial points. Griffin (1940a) came to the conclusion that big brown bats winter relatively close to their summer quarters while Rysgaard (1942) was of the opinion that they traveled many miles between winter and summer quarters. The greatest distance recorded between summering and wintering localities by Griffin was ten miles while Rysgaard reasoned that since few big brown bats were collected near the wintering quarters in the summer and a few were collected at long distances from known suitable wintering places, they must normally make quite long migrations. Reynolds (1942) recorded one adult female wintering 3.5 miles from the summer roost and Hitchcock (1949) reported two big brown bats banded in winter as being reported at 16 miles and “within a few miles” of the point of banding. Hitchcock also reported that three bats banded in the summer were subsequently recovered in buildings during the winter—all within five miles of the point of banding. All workers will agree with Hitchcocks (1949) statement: “the number of banded bats recaptured away from their places of hibernation has been disappointingly small.” This study of the survival and movements of big brown bats, Eptesicus fuscus (Beauvois), began during the winter of 1940–41 when G. N. Rysgaard and W. H. Elder started banding cave bats in Minnesota and Wisconsin, respectively. Rysgaard examined all of the caves then known in Minnesota and during his one winters work banded …

Seasonal Reproduction in the Meadow Vole

Population structure and reproductive condition of the meadow vole, Microtus pennsylvanicus , were analyzed for the period of July 1954 through July 1955. During this period there was a heavy snow cover throughout the winter and breeding was recorded for every month of the year. In the winters of 1954–55 and 1960–61, when there was very little snow cover, breeding ceased by 17 November and did not resume until about 20 March. From the 1954–55 period, 1,084; in the 1957–58 period, 37; and in the 1960–61 period, 217 meadow voles were examined.

Prenatal Survival and Loss in Some Cricetid Rodents

In spite of the fact that during recent years much stress has been placed upon the dynamic aspects of mammalian populations, very little is known about prenatal survival and loss. Detailed studies of prenatal mortality in North American wild mammals appear to have been limited to the brush rabbit (Mossman, 1955), mule deer (Robinette et al. , 1955) and meadow vole (Hamilton, 1941). The extensive work on the wild rabbit in England has been well reviewed by Brambell (1948). Other Old World studies include work on the brown rat (Perry, 1945), common shrew (Brambell, 1935), bank vole (Brambell and Rowlands, 1936), multi-mammate mouse (Brambell and Davis, 1941), and gray squirrel (Deanesly and Parkes, 1933). The estimates of intrauterine loss in these studies, depending on what information is available, varied from 9 to 43 per cent. This discussion presents data gathered in Minnesota between 1950 and 1955 on the meadow vole ( Microtus pennsylvanicus ), red-backed vole ( Clethrionomys gapperi ), woodland deer mouse ( Peromyscus maniculatus gracilis ) and the prairie deer mouse (P. m. bairdii ). All of the red-backed voles and woodland deer mice and part of the meadow voles were taken from the vicinity of Basswood Lake, Lake County, Minnesota, and all of the prairie deer mice and most of the meadow voles were taken from the Rosemount Agricultural Experiment Station in Dakota County, Minnesota. The collecting of material at Basswood Lake was partially supported by the Quetico-Superior Wilderness Research Center. This contribution is Paper No. 3548, Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul, Minnesota. In order to make a thorough analysis of intrauterine mortality rates it is necessary to know the number of ova ovulated, the number that are fertilized, the number of zygotes that implant and the number of embryos that survive to parturition. Our data only partially fulfill …

Winter Home Ranges of the Red-Backed Mouse and White-Footed Mouse

A study of the home ranges of the white-footed mouse, Peromyscus leucopus , and the red-backed mouse, Clethrionomys gapperi , was carried out in northern Anoka County, Minnesota, during the winter and while the ground was covered with snow. Trap-revealed home ranges averaged 0.27 and 0.25 acres, respectively, when calculated by the minimum-home-range method and 200 and 217 feet, respectively, when calculated by the greatest-diameter method. The animals restricted their movements for the most part to protected areas such as brush piles and under logs rather than traveling over the whole area as they appeared to do in the summer and fall. Temperatures as low as −19°F did not prevent the animals from moving about.

Effects of Pregnancy on the Spleen in Mice

Spleen size was analyzed in 2368 wild white-footed mice, Peromyscus leucopus , in Minnesota. Sex, season and type of death (chloroform or killer trap) did not affect spleen size. Females in late pregnancy showed an average increase of 50% in size of spleen. The cells in the nodules of spleens of pregnant mice were found to have large vesicular nuclei. It is suggested that this may be a reaction to an antigen produced by the embryos. Normal spleen size varied greatly (15–72 mg in animals of the same size), the S.D. being 13.6. Spleen weight versus body length is a straight line.

The immature stages of the genus Hoplopleura (Anoplura: Hoplopleuridae) in North America, with descriptions of two new species

The immature stages of the genus Hoplopleura are but little known. Of the known North American species only a few have been described or illustrated. Ferris (1921, 1951) illustrated 1 stage of H. acanthopus (Burm.) and H. arboricola K. and F., and Pratt and Karp (1953) illustrated all stages of H. oenomydis Ferris. In addition to this, a brief description of 1 stage of H. hirsuta Ferris (Ferris, 1921) and H. oryzomydis P. and L. was made by Pratt and Lane (1951). In the course of collecting specimens for quantitative studies on louse populations, numerous immature stages have come to hand representing most of the described North American species. All stages of North American species have been collected by us with the exception of H. oenomydis, H. hirsuta and H. oryzomydis. Specimens representing H. oenomydis have been made available to us through the courtesy of Dr. Harry Pratt of the C.D.C. in Atlanta. Skins of Oryzomys palustris and Sigmodon hispidus from which H. hirsuta and H. oryzomydis were recovered were made available to us by Dr. Norman Negus of Tulane University. The adult stages have all been carefully described and precisely illustrated by Ferris (1921, 1951), and also to some extent by Pratt and Lane (1951). Keys to the adult stages are also available in Ferris (1951) and Pratt and Lane (1951). In the present paper, in addition to the key and descriptions of all immature stages, 2 new species are described, 1 of which is readily distinguished in both adult and nymphal stages and another which can be distinguished only in the immature stages. Characters are also considered which will more readily permit the separation of H. arboricola from H. erratica in adult stages. The several nymphal instars are easily recognized, since in any long series of specimens at least a few nymphs will be found on the point of molting. Succeeding instars are at this time visible within the nymphal skin of the preceding stage. It is apparent in this material that there are 3 nymphal stages. It is evident that the North American species of the genus are separable into 3 groups. Those nymphs found on chipmunks and tree squirrels (H. arboricola, H. erratica, and H. sciuricola) have 5 visible pairs of minute abdominal spiracles. Those found on cricetid rodents have no such spiracles visible in any immature stages. The 1 species found on the flying squirrel (H. trispinosa) lacks abdominal spiracles as a nymph, but has the anal lobes apically setose in all stages, a condition not evident in the other 2 groups. The lice of chipmunks and tree squirrels also have conspicuous dorsal and ventral abdominal setae in addition to the marginal

Seasonal Population Changes in the Prairie Deer Mouse

Population turnover, structure and reproduction of Peromyscus maniculatus bairdii were analyzed for the period of July 1954 through July 1955, based on samples totaling 2112 animals. The breeding season started about 1 April and ended by 30 September, with an occasional female becoming pregnant in late March and a few producing young in October. Females in subadult and adult pelage produced litters at the rate of one every 27 to 30 days during the breeding season. During the first half of the breeding season from 17 to 34% of the young born survived to become independent, whereas during the latter half of the season 36 to 61% survived this long. During the snow-free period animals old enough to be independent were lost at the rate of about 40% per month, whereas during the winter the mortality rate was about 26% per month.

Nosopon clayae sp. n. (Mallophaga: Menoponidae) from Pernis apivorus

Nosopon clayae sp. n. is described from the type host, Pernis apivorus (Linn.), the honey buzzard, from Sweden. While studying the menoponid lice from raptors, we obtained a collection of four females and four males of an undescribed species of Nosopon Hopkins, 1950, from a honey buzzard, Pernis apivorus (Linn.). These lice were received from Dr. Theresa Clay, British Museum (Natural History), to whom they had been sent by Dr. H. Stenram, Zoological Institute, Lund, Sweden. Nosopon clayae sp. n. Female: Chaetotaxy and structure as in Figure 1. Minute middorsal head setae; occipital setae long. Prothorax marginally with three short and five long setae on each side. Metasternal plate with 6 to 8 setae. Abdomen with tergocentral setae all long and essentially similar: 7 to 8 on I, 8 on II to VII, and 5 to 6 on VIII. Single row of sparsely distributed anterior tergal setae: 0 to 1 on I, 4 to 6 on II, 3 to 7 on III, 5 to 6 on IV, 4 to 5 on V, 1 to 5 on VI, 0 to 1 on VII, and 0 on VIII. Postspiracular setae very long on all segments. Sternites II to VII with marginal and 1 to 2 irregular anterior rows of medium setae. Vulva with 16 to 17 evenly spaced marginal setae. Anal fringe with 11 to 13 ventral and 14 to 16 dorsal regularly spaced setae, all much the same size except for 1 or 2 longer and stouter lateroventral setae. Measurements (in millimeters): preocular width, 0.48 to 0.50; temple width, 0.60 to 0.62; head length, 0.33 to 0.35; prothorax width, 0.40 to 0.42; metathorax width, 0.47 to 0.51; total length, 1.73 to 1.98. Male: Chaetotaxy and structure, with exception of ventral terminal abdominal segments, similar to that of female. Tergocentral setae: 8 on I to VI, 7 to 8 on VII, and 4 to 6 on VIII. Anterior tergal setae: 0 to 1 on I, 1 to 3 on II, 2 to 3 on III and IV, 0 to 2 on V, 0 to 1 on VI, and 0 on VII and VIII. Received for publication 15 April 1963. * Paper No. 5083, Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul 1, Minnesota. Genitalia (Fig. 2) relatively simple, without evident penis, genital sac, or associated genital sclerites. Measurements (in millimeters): preocular width, 0.44 to 0.45; temple width, 0.54 to 0.56; head length, 0.31; prothorax width, 0.35 to 0.40;