George A. Feldhamer

HOME RANGE AND NEST USE OF THE GOLDEN MOUSE (OCHROTOMYS NUTTALLI) IN SOUTHERN ILLINOIS

Abstract To estimate home range and ascertain nesting habits of golden mice (Ochrotomys nuttalli), 19 individuals were radiocollared and their nests located. Individual home-range area did not significantly vary with sex, season, or number of nests used; minimum convex polygon and adaptive kernel estimates ranged from 0.18 to 1.33 ha and from 0.33 to 2.82 ha, respectively. Home-range overlap among individuals was considerable. No difference existed in distances between nests used by the same individual. Females used more arboreal nests; males used more ground nests. Only males exclusively used ground nests. Significant variables associated with placement of both ground and arboreal nests were distance to nearest vines and undergrowth, densities of herbaceous and woody stems, and density of understory <0.5 m at 1 m from the nest. Depth of leaf litter and size (dbh) of nearest tree also predicted placement of ground nests. Density of understory, 1.6–2.0 m high, and number of herbaceous stems significantly predicted placement of arboreal nests. The golden mouse may be less of a habitat specialist than believed. Management for invasive or early successional plant species may enhance habitat for this species.

Trap-response heterogeneity of house mice (Mus musculus) in outdoor enclosures

We studied extrinsic and intrinsic factors affecting trap-response heterogeneity in house mice ( Mus musculus ) in eight 0.1-ha outdoor enclosures. Changes in density did not significantly affect proportions of mice captured. Overall, greater proportions of males than females were captured. Adults were captured more often than subadults, and subadults were captured more often than juveniles. Extrinsic factors including relative humidity, temperature, and decreased vegetative cover affected proportions of mice captured for various age and sex classes. Two measures of individual trap-response heterogeneity were used: percentage of times an individual could have been captured that it actually was and mean number of trap sessions between captures. Significant yearly variation occurred in both measures. Trap response heterogeneity among sexes did not emerge until the mice were subadults or adults. There was significant yearly variation in proportions of recruits entering traps as juveniles, subadults, or both. Our findings indicate that there is substantial intrinsic heterogeneity, modified by external factors, in capture rates of the house mouse. Data collected to assess population size, survival rates, home range, and other life-history characteristics collected by live trapping warrant cautious interpretation.

Prey Consumed by Eight Species of Insectivorous Bats from Southern Illinois

Abstract We collected data on the diet of eight species of insectivorous bats (Chiroptera, Vespertilionidae): big brown bats (Eptesicus fuscus), red bats (Lasiurus borealis), evening bats (Nycticeius humeralis), northern myotis (Myotis septentrionalis), little brown myotis (M. lucifugus), Indiana myotis (M. sodalis), southeastern myotis (M. austroriparius) and eastern pipistrelles (Perimyotis subflavus). Bats were mist netted during the summers of 1999 and 2000 at 41 forest sites throughout southern Illinois. We analyzed prey remains in fecal pellets of 305 individuals to assess diet similarity among species and relationships between bat body mass and prey diversity and hardness. Larger species included big brown bats and evening bats that ate primarily hard-bodied beetles (Coleoptera). These bats had the greatest dietary similarity index value compared with the other chiropterans in the community, and the highest hardness indices of prey consumed. Red bats, second only to E. fuscus in mean body mass, ate more soft bodied moths (Lepidoptera) and leaf hoppers (Homoptera) than beetles. Smaller bats, including three species of Myotis, consumed the greatest diversity of prey and were generally grouped together in diet similarity indices. Little brown myotis, northern myotis and Indiana myotis fed primarily on moths and beetles. Northern myotis and little brown myotis also fed extensively on spiders, suggesting significant gleaning behavior. Unlike other Myotis, the southeastern myotis had a low dietary diversity index and fed primarily on caddisflies (Trichoptera), as did eastern pipistrelles. Pipistrelles and myotines had the lowest hardness indices of prey consumed. Bats in southern Illinois exhibited landscape level (macroscale) feeding patterns consistent with the predicted relationship between body size and hardness of prey consumed, while at the local, site-specific level (microscale) they foraged with extensive overlap among similar-sized species, especially most Myotis. Regional differences in diets were minimal within the same assemblage of bat species in southern Indiana.

Microhabitat Selection by Golden Mice (Ochrotomys nuttalli) at Arboreal Nest Sites

Abstract We measured habitat characteristics at 34 arboreal nest sites of golden mice (Ochrotomys nuttalli) and 34 paired random sites from May–Sept. 1997. Microhabitat was significantly different between the two types of sites. Arboreal nest sites differed from random sites in 5 of the 12 habitat characteristics measured including: more climbing vines and woody vegetation, greater horizontal vegetative cover as measured by a density board at a distance of both 3 m and 6 m from the nest and closer to understory trees. The presence of thick vegetation at arboreal nest sites may provide increased protection from predators, increased substrate for attachment of nests, protection from inclement weather and thermoregulatory advantages. Management strategies that increase the density of understory vegetation in areas where golden mice occur will enhance populations by improving nesting habitat and increasing recruitment and survival.

URBAN HABITAT: A DETERMINANT OF WHITE- FOOTED MOUSE (PEROMYSCUS LEUCOPUS) ABUNDANCE IN SOUTHERN ILLINOIS

Abstract The objective of this study was to assess whether differences in abundance of white-footed mice (Peromyscus leucopus) were related to habitat features within and surrounding 60 sampled bottomland forest patches. Habitat features included patch size, patch shape, and landuse within a 300-m buffer surrounding each patch. During 18,000 trap nights, we captured 1,308 white-footed mice within approximately 3,110 ha of bottomland forest. Type of habitat surrounding a patch was a significant determinant of white-footed mouse abundance. Sample sites where less than 10 individuals were captured were surrounded by a large percentage of upland deciduous forest and a low percentage of urban/other habitats. Sample sites where 30 or more individuals were captured were surrounded by a large percentage of urban/other habitats and a small percentage of upland deciduous forest. Sites where 10–29 individuals were captured were surrounded by intermediate amounts of upland deciduous forest and urban/other habitat. Although deciduous forest is necessary, it may not be the primary determinant of white-footed mouse abundance. Unsuitable habitat may surround and create islands of high density from which successful dispersion is difficult.

Habitat Partitioning, Body Size, and Timing of Parturition in Pygmy Shrews and Associated Soricids

A total of 388 shrews of four species was captured during 14 months of pitfall trapping on 20 sites located in five habitat types on Land Between the Lakes, in western Kentucky and Tennessee. The soricid community was made up of one large species ( Blarina brevicauda ), one medium-sized species ( Cryptotis parva ), and two small species ( Sorex hoyi and S. longirostris ). All species showed significant differences in frequency of capture in four of the five habitats, although there was considerable interspecific overlap in habitat use. Based on estimated age and time of capture, the major period of parturition for pygmy shrews was January through early March. Individuals entered the trappable population ca. 8 weeks later. Young pygmy shrews had attained adult body size by the time they entered the trappable population. Parturition also occurred from August through December, but at a lower rate, with few individuals born in June and July. Ninety-three pygmy shrews were captured, most from March through May. No pygmy shrews were captured from June through August, a period when 30.2% of 43 southeastern shrews were captured. These two species of small shrews, which were not significantly different in size on Land Between the Lakes, may partially segregate during summer, with pygmy shrews much less active above ground.

PLACEMENT OF NETS FOR BATS: EFFECTS ON PERCEIVED FAUNA

Abstract We used mistnets to survey bats at 41 sites throughout the Shawnee National Forest in southern Illinois during the summers of 1999 and 2000. Unlike most previous studies, we placed nets in the interior of forest stands as well as the more typical placement along edge habitats associated with water. We captured 417 individual bats representing 10 species. Of these, 168 individuals (40.3%) and 8 species were collected in interior forest. Northern long-eared bats (Myotis septentrionalis) were caught significantly more often in interior forest, whereas red bats (Lasiurus borealis), eastern pipistrelles (Pipistrellus subflavus), and big brown bats (Eptesicus fuscus) were netted more often in edge habitats. In contiguous forest, especially within the geographic range of M. septentrionalis, a more accurate measure of bat diversity and relative abundance is obtained by placing nets in interior forest as well as edge habitats.

Efficacy of the Mist-net Protocol for Indiana Bats: A Video Analysis

Abstract We mist-netted bats to test the efficacy of the US Fish and Wildlife Service Indiana Bat Protocol (IBP), which recommends monitoring nets every 20 min. We continuously videotaped mist nets while monitoring and removing bats every 20 min. We recorded 157 bats on video that approached within 10 m of the mist net. Thirty-six bats (23.1%) avoided the net, 79 (50.0%) were caught and collected, and 42 (26.9%) were caught but escaped before we returned to check the net. We recommend that researchers check mist nets at intervals ≤ 10 minutes to potentially increase capture rates by ≥ 25%.

POPULATION DYNAMICS AND ACTIVITY OF SOUTHERN SHORT-TAILED SHREWS (BLARINA CAROLINENSIS) IN SOUTHERN ILLINOIS

Abstract We captured, marked, and recaptured southern short-tailed shrews (Blarina carolinensis) during a 30-month livetrapping study in a woodlot in Jackson County, Illinois, to compare aspects of their life history with those of the northern short-tailed shrew (B. brevicauda). A total of 106,496 trap checks (15,782 trap nights) resulted in 3,430 captures of 313 B. carolinensis from February 1996 through August 1998. Trapping mortality was only 18 individuals. Sex ratio did not differ from 1:1. Estimated population density peaked at 57 individuals/ha in late summer and autumn then declined during winter. Recruitment, including birth and immigration, peaked in spring and late summer each year. Individuals entering the population in the spring and early summer had higher survival rates than those entering in the autumn. A weak correlation was found between recruitment and precipitation, and between population density and humidity. Shrew activity (timing of captures) showed significant relationships with light condition and season. During summer, shrews were caught more frequently at night. In the winter, they were captured more frequently during the day. Capture rate was negatively related to precipitation and positively related to humidity. Population dynamics and activity patterns were similar to those of B. brevicauda.

Dental anomalies in the gray foxUrocyon cinereoargenteus and the red foxVulpes vulpes

We examined dental anomalies, including oligodonty, polydonty, connation, rotation, and misalignment in 510 gray foxes and 150 red foxes from southern Illinois (USA). Dental anomalies were significantly more common (x2 = 11.5, df = 1,p < 0.001) in gray foxes (n = 177; 34.7% of sample) than red foxes (n = 25; 16.6% of sample), and more common in male than female gray foxes (x2 = 3.88, df = 1,p < 0.05). Polydonty was very uncommon, as expected for species in which the normal dental complement is close to the primitive eutherian number. In both species, the most prevalent anomaly was loss of the last lower molar. Loss of the upper or lower first premolar was also common. Thus, oligodonty almost always involved the smaller anterior (P1 and P1) or posterior (M3) teeth of the dental arcade. Conversely, the large carnassial teeth, with complex occlusal patterns and shearing surfaces, appeared to be highly conserved with only three anomalous individuals (0.4%) among all specimens.