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A.E. Morales et al. (2021. Can. J. Zool. 99(5): 415–422) provided no new evidence to alter the conclusions of C.L. Lausen et al. (2019. Can. J. Zool. 97(3): 267–279). We present background information, relevant comparisons, and clarification of analyses to further strengthen our conclusions. The genesis of the original “evotis–keenii” study in British Columbia (Canada) was to differentiate Myotis keenii (Merriam, 1895) (Keen’s myotis), with one of the smallest North American bat distributions, from sympatric Myotis evotis (H. Allen, 1864) (long-eared myotis), using something other than the suggested post-mortem skull size comparison, but no differentiating trait could be found, leading to the molecular genetics examination of C.L. Lausen et al. (2019). We present cumulative data that rejects the 1979 hypothesis of M. keenii as a distinct species. A.E. Morales et al. (2021) inaccurately portray C.L. Lausen et al.’s (2019) question and results; present inaccurate morphological and outdated distribution data; overstate the impact of homoplasy without supporting evidence; and misinterpret evidence of population structure.

Genetic exchange and hybridization appear common among the western long-eared bats from North America. Multiple sources of evidence indicate that lineages within this group are evolving independently, despite genetic exchange. However, evidence of gene flow raises questions about the species-level status of some lineages. C.L. Lausen et al. (2019. Can. J. Zool. 97(3): 267–279) proposed that Myotis evotis (H. Allen, 1864) (long-eared myotis) and Myotis keenii (Merriam, 1895) (Keen’s myotis) are one species, not two. This conclusion is based on analyses of cytochrome b and microsatellite data suggesting gene flow between these taxa. Microsatellites are not reliable markers for identifying species because homoplasy can be a major confounding factor, which appears to be true in this case. We reanalyzed the dataset of C.L. Lausen et al. (2019) and show that it is not reliable to distinguish between gene flow or homoplasy, and that these data do not support the conclusion that M. evotis and M. keenii represent a single species. Previous morphological and genomic studies indicate that these are separate species despite previous genetic exchange between them. Failing to recognize that gene flow can occur between independently evolving lineages is counterproductive for conservation because it can lead to neglect of important independent lineages, and likewise failing to use proper tools to delimit species is counterproductive to efforts to quantify biodiversity and design conservation strategies.

Intraspecific variation in diet and (or) foraging behaviour is one way in which species are able to occupy wide geographical areas with variable environments. The little brown bat (Myotis lucifugus (Le Conte, 1831)), a primarily aerial insectivorous bat, consumes spiders in low temperatures at the start and end of summer in Northwest Territories, Canada, but it consumes spiders all summer, even during high aerial insect abundance, in Alaska, USA. There are no competitors of M. lucifugus in Alaska, but there are in Northwest Territories, suggesting that aerial insect abundance and competition from gleaning bats influences when M. lucifugus consumes spiders. In the Kananaskis area of the Rocky Mountains of Alberta, Canada, we investigated spider consumption by M. lucifugus and the long-eared myotis (Myotis evotis (H. Allen, 1864)), a species more adept at gleaning, to better understand when bats consume spiders. Fecal sample analysis indicated that M. evotis consumed spiders all season long, with greater consumption when the bats were caught near water. Myotis lucifugus did not consume spiders at all. This suggests that M. lucifugus opportunistically consumes spiders when encountered, but does not encounter them in Kananaskis where it forages primarily over open water, unlike in Northwest Territories where it forages in the interior of forests and may encounter spiders more frequently.

Recognizing delineations of gene flow among groups of animals can be challenging but is necessary for conservation and management. Of particular importance is the identification of species boundaries. Several physical and genetic traits have been used with mixed success to distinguish Myotis keenii (Merriam, 1895) (Keen’s myotis) and Myotis evotis (H. Allen, 1864) (long-eared myotis), but it is unclear whether species distinction is biologically warranted. We generated 12–14 microsatellite locus genotypes for 275 long-eared Myotis representing four species — M. keenii, M. evotis, Myotis septentrionalis (Trouessart, 1897) (northern myotis), and Myotis thysanodes Miller, 1897 (fringed myotis) — from across northwestern North America and 23 Myotis lucifugus (Le Conte, 1831) (little brown myotis) as the outgroup. Population genetic analyses revealed four well-defined groups (species): M. septentrionalis, M. thysanodes, M. lucifugus, and a single group comprising M. keenii and M. evotis. We document high rates of gene flow within M. evotis/M. keenii. Cytochrome b gene (mtDNA) sequencing failed to resolve morphologically identifiable species. We highlight the importance of geographically thorough investigation of genetic connectivity (nuclear markers) when assessing taxonomic status of closely related groups. We document a morphometric cline within M. evotis/M. keenii that may in part explain earlier analyses that led to the description of the smaller bodied M. keenii (type locality: Haida Gwaii). We conclude that M. keenii does not qualify as a genetic or biological species.

Glen Canyon National Recreation Area covers large and geographically unique regions of southern Utah and northern Arizona. However, multiple surveys of bats from 1952 to 2017 have not been published. Prior to 2015, most bat surveys in the recreation area were conducted using mist nets only and did not include acoustic monitoring. In this paper we compile records of bats found in Glen Canyon National Recreation Area from 1952 to 2017, including records from our recent surveys using both mist nets and acoustic sampling. During our recent surveys, 2 new species were captured (Nyctinomops macrotis and Lasionycteris noctivagans), and 2 other new species were documented using acoustic detection (Myotis evotis and Eumops perotis), bringing the total documented bat species in Glen Canyon National Recreation Area to 17 species. This paper sheds light on the diverse bat assemblage of Glen Canyon National Recreation Area that will serve as a baseline for future research and conservation efforts.

Resource selection models and estimates of home range provide land managers with information that is required to make informed decisions regarding wildlife conservation and management across multiple spatial scales. We used radiotelemetry to examine resource selection and space use of Myotis evotis (western long-eared myotis) in a western juniper (Juniperus occidentalis) woodland in eastern Oregon, United States. Small sample sizes likely constrained our ability to detect differences between estimates of home range size for males (x = 424.2 ha, SE = 187.2) and lactating females (x = 205.85 ha, SE = 47.94). Our estimates are among the largest reported for Myotis species, but likely are biased low due to low ambient temperatures and the methods we used to estimate home range. Best resource selection models for males and lactating females differed across spatial scales, based on Akaike's information criteria with a bias correction term for small sample size (AICc). At the home range scale, resource use by lactating females was negatively related with distance from water, whereas males selected areas with > 0–10% canopy cover over areas with no canopy cover. At the landscape scale, resource use by males and lactating females decreased with increasing distance from roosts and water sources. Additionally, lactating females avoided areas with > 20% canopy cover more than areas with no canopy cover. These results emphasize the importance of managing pre-settlement woodlands located near roost sites and water sources for variable tree densities to maintain foraging areas for bats.

Little work has focused on species presence, distributions, and habitat use of bats in the Great Plains of North America. In particular, no previous study has attempted to determine if bats are utilizing hibernacula during the winter months in North Dakota. The current lack of information regarding bat species presence during the winter months in North Dakota can have great conservation implications. Pseudogymnoascus destructans, the fungal pathogen responsible for white-nose syndrome (WNS) in bats across the United States and Canada, has led to great concern for wildlife managers. For many of the areas where WNS is present, information about the presence and location of hibernacula are known, allowing for close monitoring of the spread of the disease. However, some locations within the predicted path of WNS still lack information as to bat species presence during the winter months. Due to mortality rates sometimes reaching upwards of 100% as a result of WNS infection, filling in these information gaps is critical for conservation research. The purpose of this study was to determine if the badlands region of North Dakota supports over-wintering bat communities, document both utilized and potential hibernacula, and develop a Geographic Information Systems model in the program MaxEnt to be used for future studies and wildlife managers. Six species were positively identified in the badlands region of North Dakota during the pre-hibernation and winter hibernation periods: Big Brown Bat (Eptesicus fuscus), Silver-haired Bat (Lasionycteris noctivagans), Little Brown Bat (Myotis lucifugus), Long-eared Myotis (Myotis evotis), Townsend's Big-eared Bat (Corynorhinus townsendii), and Western Small-footed Myotis (Myotis ciliolabrum). Habitat suitability modeling was employed to model potential hibernacula in the study area. Knowledge of these potential hibernacula could be of great importance to wildlife managers, and results from this study may be used by regional wildlife managers to develop strategies for curtailing the spread of this disease into North Dakota.

378. Long-eared Myotis Myotis evotis French: Murin a oreilles longues / German: Langohriges Mausohr / Spanish: Ratonero de orejas largas Other common names: Western Long-eared Bat, Western Long-eared Myotis Taxonomy. Vespertilio evotis H. Allen, 1864, type locality not given. Restricted by G. S. Miller, Jr. in 1897 to “Monterey, Caljifornia].,” USA. Subgenus Pyzonix; lucifugus species group. Myotis evotis is most closely related to M. thysanodes, M. keenii, M. occultus, and the paraphyletic M. lucifugus (specifically M. lL carissimus and M. l. pernox, which likely represent distinct species), although relationships among these species and the clade including M. sodalis, M. volans, M. lucifugus, M. L. relictus, and M. I. alascensis are not well resolved. Six subspecies recognized. Subspecies and Distribution. M.e.evotisH.Allen,1864—coastalSWUSA(CW&SWCalifornia). M. e. chrysonotus J. A. Allen, 1896 — SW Canada (SE British Columbia, S Alberta, and S Saskatchewan) and W USA (most of Montana, W & NE North Dakota, NW South Dakota, SE Oregon, S Idaho, Wyoming, inland California, Nevada, Utah, Colorado, and extreme N New Mexico). M. e. jonesorum Manning, 1993 — SW USA (N & E Arizona and W New Mexico). M. e. micronyx Nelson & Goldman, 1909 — NW Mexico (N Baja California). M. e. milleri Elliot, 1903 — NW Mexico (S Baja California). M. e. pacificus Dalquest, 1943 — SW Canada (SW British Columbia and Vancouver I), and NW USA (Washington, most of Oregon, N Idaho, NW Montana, and NW California). Descriptive notes. Head-body 43-52 mm, tail 36-45 mm, hindfoot 810 mm, ear 18— 24 mm, forearm 37-40 mm; weight 4-9 g. Fur of the Long-eared Myotis is long and fluffy. Dorsum is yellowish to dark brown, darkest in Pacific Northwest; venteris paler. Bare face, ears, and membranes are black. Ears are very long and extend well beyond nose when laid forward. Calcar is unkeeled orslightly keeled. Skull has gradually rising forehead region; sagittal crest is usually present but inconspicuous; skull is relatively narrow overall; and braincase is ovoid when viewed from above, bulging posteriorly beyond lambdoidalcrests. Upper premolars are not crowded and in line in tooth row; molarsare relatively large; and M? has marked angle between parastyle and mesostyle. Chromosomal complement has 2n = 44 and FN = 52. Habitat. Humid coastal areas to montane forests, including mixed coniferous forests, dry forests, subalpine forests, semiarid shrublands, sage, chaparral, and agricultural areas from sea level up to elevations of ¢. 2830 m (Wyoming). Food and Feeding. [.ong-cared Myotis primarily hunt by aerial hawking but occasionally glean prey off of surfaces. They eat variousinsects but primarily Lepidoptera and Coleoptera. In Arizona, diet included Lepidoptera, Coleoptera, Diptera, Neuroptera, Hymenoptera, Hemiptera, and Homoptera. Odonata has also been recorded in diets in Montana. When sympatric with the South-western Myotis (M. auriculus), the Longeared Myotis primarily eats Coleoptera rather than Lepidoptera. Long-eared Myotis bats also appear to exhibit sexual differences in food selection, with males eating significantly more moths than females. Breeding. Pregnant Long-eared Myotis have been collected from mid-May to mid-July throughout the distribution, and volant young have been reported from late July in New Mexico. This suggests that births occur around June to mid-July. Females give birth to one young. Oldest recorded individual was a 22-year-old male. Activity patterns. L.ong-eared Myotis use various types of day roosts (e.g. abandoned buildings, tree hollows, under loose bark, among timber, caves and mines, crevices, and sinkholes). They leave roosts to forage relatively late in the evening and often continue foraging later into the night, often later than midnight. In Arizona, theyleaf roosts ¢.30 minutes after sunset and foraging for a little more than two hours, and in Oregon in August, they emerged 10-40 minutes after full darkness. They hibernate through winter. Calls are steep FM sweeps, with start frequencies of 59-9-100-2 kHz (mean 71-2 kHz), end frequencies of 31-5-48-6 kHz (37-1 kHz), peak frequencies of 45-58-4 kHz (50-8 kHz), and durations of 0-3-2-7 milliseconds (1-1 milliseconds) in Alberta. Movements, Home range and Social organization. Long-eared Myotis roost in small groups or alone, with males and some non-reproducing females living alone or in small groups in summer and reproductive females forming small maternity colonies of up to 30 individuals. They might migrate short distances from summer to winter roosts and hibernacula. They have been recorded sharing roosts with Townsend’s Big-eared Bats (Corynorhinus townsendii) in Idaho. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Longeared Myotis appears to be widespread and common throughoutits distribution and does not appear to face any major threats. Habitat loss and roost disturbance might be major risks in the future; they can be considered pests because of their preference to roost in attics. Bibliography. Arroyo-Cabrales & Alvarez-Castafieda (20179), Chruszcz & Barclay (2002b, 2003), Dalquest (1943), Faure & Barclay (1994), Faure et al. (1990), Findley (1972), Gannon & Réacz (2006), Jones, C. (1965), Jones, J.K. & Choate (1978), Jones, J.K., Lampe et al. (1973), Kellner & Harestad (2005), Larrison & Johnson 1981), Manning (1993), Manning & Jones (1989), Miller (1897), Morales & Carstens (2018), Morales et al. 2017), Nixon et al. (2009), Rancourt et al. (2005), Rust (1946), Snider et al. (2013), Solick & Barclay (2006), Vonhof & Barclay (1996, 1997), Waldien et al. (2000), Whitaker & Wilson (1974), Whitaker et al. (1977), Whitlow Hall (1933), van Zyll de Jong & Nagorsen (1994)., Published as part of Don E. Wilson & Russell A. Mittermeier, 2019, Vespertilionidae, pp. 716-981 in Handbook of the Mammals of the World – Volume 9 Bats, Barcelona :Lynx Edicions on pages 928-929, DOI: 10.5281/zenodo.6397752

We conducted a survey of the bat fauna of Desert National Wildlife Refuge (DNWR) in Nevada during 2008–2014. Our objectives were (1) to determine the species present at DNWR by mist-netting at likely bat drinking areas; (2) to compare the bat fauna at White Spot Spring at DNWR to the fauna documented there in 1962–1967; and (3) to assess the possible importance of artificial water sources to bats on this highly arid landscape in relation to an ongoing drought. We captured 480 bats of 10 species in mist nets over drinking water sources; species identifications are documented by voucher specimens. In order of frequency of capture, species and numbers of individuals captured were as follows: canyon bat (Parastrellus hesperus), 223; combined California myotis and western small-footed myotis (Myotis californicus/M. ciliolabrum), 157; long-legged myotis (Myotis volans), 55; long-eared myotis (Myotis evotis), 12; Townsend's big-eared bat (Corynorhinus townsendii), 12; fringed myotis (Myotis thysanodes)...

Habitat use by bats in forests varies with environmental variables, clutter, and prey availability, but few studies have looked at habitat use as a function of forest composition and forest age across a range of elevations. We examined factors influencing habitat use of forest-dwelling bats in southwestern British Columbia using ultrasonic detection. We measured activity of three bat foraging guilds in four forest types and three age classes from May to August 2000 and 2001. Habitat use varied with forest composition and stand age, but not always as we predicted. Activity of open-habitat foragers (large bats) was greatest in higher elevation forests and in young forests. In contrast, activity of the long-eared myotis (Myotis evotis (H. Allen, 1864)), a gleaner, was greater in lower elevation black cottonwood (Populus trichocarpa Torr. & A. Gray ex Hook.) and cedar–hemlock stands. Myotis evotis activity also increased with increasing forest age. Activity of edge and gap insectivores (genus Myotis Kaup, 1829) was greater in black cottonwood stands and old Interior Douglas-fir stands than in other forest types. The probability of detecting foraging Myotis was highest in black cottonwood stands. Myotis activity did not show a clear pattern with forest age. Our results demonstrate the importance of black cottonwood riparian forests to foraging Myotis, as well as the importance of older, low-elevation forests.

Few bat inventories have taken place in Northwest Territories (NWT), Canada, an area currently known to be the northernmost extent of the ranges of at least 6 bat species. Only 2 species of bats, the Northern Myotis (Myotis septentrionalis) and Little Brown Myotis (M. lucifugus), were previously known from the Nahanni National Park Reserve in the southwestern NWT. We used mistnets (15 nights) and AnaBat ultrasound detectors (23 nights) to survey bats in the South Nahanni River Watershed and surrounding area, to undertake the first formal survey of bats in the Northwest Territories. We confirmed the presence of the 2 species formerly documented from the area, as well as an additional 5 species not previously recorded from the region, including: Long-eared Myotis (Myotis evotis), Long-legged Myotis (M. volans), Big Brown Bat (Eptesicus fuscus), Hoary Bat (Lasiurus cinerus), and Eastern Red Bat (L. borealis). Four species were captured in mistnets (Northern Myotis, Little Brown Myotis, Long-eared My...

All 16 species of bats known to occur in western Colorado are found at Mesa Verde National Park (MVNP) in the southwestern United States. Since 1996, wildfires have burned more than 70% of MVNP (>15,000 ha), potentially altering food and roosting resources for bats. During the summers of 2006–2007, we investigated roost use by reproductive female western long-eared myotis (Myotis evotis). We located 33 bat roosts in rock crevices and 1 in a juniper snag. All but 2 of the roosts were in unburned habitat. Bats roosted alone or in small groups (≤3 individuals) and switched roosts frequently (1–7 roosts per bat, median = 1.5 roosts per bat, SE = 0.5 roosts per bat). We compared occupied roosts with randomly selected unoccupied crevices and used an information theoretic approach to determine which variables were most important in determining roost use at microhabitat and landscape scales. At the microhabitat scale, maternity roosts were higher above the ground and deeper than random, unoccupied rock c...

We determined the presence of rabies-virus-neutralizing antibodies (RVNA) in serum of 721 insectivorous bats of seven species captured, sampled, and released in Colorado and New Mexico, United States in 2003-2005. A subsample of 160 bats was tested for rabies-virus RNA in saliva. We sampled little brown bats (Myotis lucifugus) at two maternity roosts in Larimer County, Colorado; big brown bats (Eptesicus fuscus) at three maternity roosts in Morgan County, Colorado; and big brown bats at five maternity roosts in Larimer County. We also sampled hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) captured while drinking or foraging over water in Bernalillo County, New Mexico and at various locations in Larimer County. Big brown bats, little brown bats, long-legged myotis (Myotis volans), long-eared myotis (Myotis evotis), and fringed myotis (Myotis thysanodes) were also sampled over water in Larimer County. All species except long-eared myotis included individuals with RVNA, with prevalences ranging from 7% in adult female silver-haired bats to 32% in adult female hoary bats. None of the bats had detectable rabies-virus RNA in oropharyngeal swabs, including 51 bats of 5 species that had RVNA in serum. Antibody-positive bats were present in nine of the 10 maternity colonies sampled. These data suggest that wild bats are commonly exposed to rabies virus and develop a humoral immune response suggesting some degree of viral replication, but many infections fail to progress to clinical disease.

Understanding how environmental factors affect activity, number, and spatial distribution of bats in an area is necessary for interpreting capture rates and assessing abundance. Over a 34-year period, we examined the relationship between amounts of precipitation and activity of bats along a canyon floor in the San Mateo Mountains of New Mexico in the southwestern United States. For 1 night during each of 19 summers, we used identical sampling techniques to monitor this assemblage of insectivorous bats. Years included droughts with minimal surface water and wet years with abundant surface water in the canyon. Marked differences in available drinking water resulted in striking differences in yearly captures of bats, with a 30.8-fold difference between the fewest and most captures (6 versus 185 adults). Capture rates increased with less precipitation before sampling. In the 3-decadal period, precipitation accounted for 66% of the variation in capture rates, providing support that bats concentrate around accessible water to drink when surface water is scarce. Captures also were influenced by relative humidity on nights of sampling. From 1971 to 2005, we detected no change in species composition in this bat assemblage of 8 species, and after accounting for effects of precipitation, we detected no declines in population size for the 2 most common species, the long-eared myotis (Myotis evotis) and long-legged myotis (M. volans). Our study demonstrates the importance of long-term data sets to help elucidate patterns of variability in capture data and highlights the importance of how yearly variation in climate affects the behavior and ecology of bats.

We investigated roost use by western long-eared bats (Myotis evotis), including roost fidelity, movement between roosts and the size of roosting home-ranges. We expected reproductive females, especially lactating females, to exhibit higher roost fidelity and to move shorter distances between roosts than males or nonreproductive females. Individuals generally switched roosts every 1 or 2 d. Despite their low roost fidelity, individuals occupied small roosting home-ranges (

We surveyed bats using echolocation calls near inactive mines in the western Great Basin from 2003 to 2007. We identified 14 species of bats during our surveys, with Myotis lucifugus and Lasionycteris noctivagans found at 9 sites and Myotis evotis and Tadarida brasiliensis at 7 sites; all other species were found at less than one-half of the sites. Euderma maculatum, a state-protected species in Nevada, was recorded at 2 sites. Our work provides information that will be useful in managing bat habitat, especially with regard to mining activities.

Forest management activities influence habitat suitability for bats, and knowledge of the roosting ecology of bats is fundamental to developing strategies for conserving bats in managed forests. Information on use of roosts by multiple species of bats in a given area may provide insight into interspecific ecological patterns and could improve management prescriptions to provide habitat for bats through time across diverse ownerships and over multiple spatial scales. We investigated use of conifer snags as roosts by females of 3 species of forest-dwelling bats in Douglas-fir (Pseudotsuga menzesii) forests in the western Oregon Cascade Range. We radiotagged 29 female big brown bats (Eptesicus fuscus), 55 long-legged myotis (Myotis volans), and 27 long-eared myotis (Myotis evotis) and located 42, 105, and 24 snag roosts for the 3 species, respectively. All 3 species most frequently used Douglas-fir snags and in similar proportions to their availability. Big brown bats and long-legged myotis rarely roosted in stands

In the fall of 2005 and spring and summer of 2006, The Nature Conservancy, in cooperation with the Washington Department of Fish and Wildlife and Cascadia Research Collective, conducted a mammal inventory on McChord Air Force Base (MAFB). The military has a vested interest in maintaining habitat and species by congressional mandate and the corresponding burden of recovery. Six major habitat types were designated for trap-line transects; additional directed efforts were employed to target specific species. The resulting effort documented the presence of 36 species, eight of which were bats. Documented species of note include the western gray squirrel (Sciurus griseus), a state “threatened” species, detected by hair-snag tubes; long-eared myotis (Myotis evotis); long-legged myotis (Myotis volans); and the Yuma myotis (Myotis yumanensis). Mammalian diversity on MAFB was influenced by three factors: water (either open water or wetland habitat); large, contiguous tracts of undeveloped acreage; and continuity with Fort Lewis, a large military base immediately adjacent to MAFB. Additionally, Scotch broom (Cytisus scoparius), an invasive woody shrub, was found to support limited mammalian diversity, with the fewest species documented in this habitat type. Given the impending changes due to development, ownership, and climate, this survey will be useful to managers as a baseline for focused species efforts and future comparisons.Environmental Practice 10:116–124 (2008)

The costs and benefits of torpor may vary across the range of widespread heterothermic species, resulting in different thermoregulatory patterns and other behaviours for individuals inhabiting different environments. We compared torpor use and roosting behaviour for rock-roosting populations of western long-eared bats Myotis evotis living in the mountains and prairies of Alberta, Canada. We monitored body temperatures and located roosts for pregnant and lactating females using radio-telemetry. We also took roost measurements, and assessed roost microclimate using temperature dataloggers. Females in the mountains entered torpor less frequently and spent less time in torpor than bats in the prairies, supporting our hypothesis that reproductive time constraints in the mountains outweigh the benefits of torpor. Alternatively, increased torpor use in the prairies may be attributed to a greater need for water conservation. Females in the mountains minimized thermoregulatory costs and maintained homeothermy by selecting exposed roosts with warm microclimates during pregnancy, and then switching to clustering with other individuals during lactation when conditions were cooler. In the prairies, females roosted alone in cooler, less exposed roost types, which facilitate the use of torpor. Our results illustrate the importance of considering geographic variation in behaviour across the range of a species.

We compared the external morphology of western long-eared myotis (Myotis evotis) living in mountain (cool, wet) and prairie (warm, dry) environments in southern Alberta to test whether flight permits genetic exchange between populations thereby limiting divergence in morphological traits. We measured size of the body (forearm length and mass), ears, and wings for males and females. Ears and wings were significantly larger for bats in the mountains, suggesting that there is limited gene flow between populations despite their geographic proximity, and adaptation to differences in aridity or foraging habitat. However, body size was similar between environments, suggesting that either M. evotis possesses an ecologically flexible body type or that differences in extremity size are the result of environmentally induced phenotypic plasticity. Within environments, females were larger than males for all morphometrics. However, the degree of dimorphism was similar for mountain and prairie populations, indicating that dimorphism is not the result of different thermoregulatory needs in these populations.

Entering torpor can yield significant energy savings for temperate-zone bats but can be costly for reproductive females by slowing fetal development and reducing milk production. We studied western long-eared bats (Myotis evotis (H. Allen, 1864)) in the Rocky Mountains of Alberta to test the hypothesis that different costs of torpor result in different patterns of thermoregulation and roosting behaviour for reproductive and nonreproductive females. We radio-tracked bats to monitor body temperatures and locate roosts. We took roost measurements and inserted temperature data loggers to measure roost microclimate. Bats entered torpor frequently, but nonreproductive females spent longer periods in torpor, had lower minimum body temperatures, and entered deep torpor more often than reproductive females did, supporting the hypothesis that entering torpor is more costly for reproductive individuals. Roosts were located mainly in rock fields on steep, open, south-facing slopes. Reproductive females roosted in crevices between rocks located above or on the surface of the ground. Roosts warmed rapidly and reached warm daytime temperatures. Females roosted alone during pregnancy but formed small colonies within roosts during lactation when ambient conditions were cooler. Clustering may reduce thermoregulatory costs for both adults and young. Nonreproductive females roosted mainly alone in crevices in the ground. These roosts had cooler, more stable microclimates, allowing females to enter deeper bouts of torpor and remain torpid longer.

Ecomorphological analysis was used to evaluate ecological relationships between 2 species of bats, Myotis auriculus and M. evotis. We imaged jaws and skulls of 242 specimens from 20 localities within the range of both taxa, emphasizing their southwestern regional area of sympatry. Using traditional morphometric and geometric morphometric methods, values for characters taken from dentaries of both species were analyzed in detail. Both methods detected character displacement and allowed us to detect differences in jaw size and shape within both species. The morphological difference in jaw shape is more emphasized within sympatric populations of M. evotis than in M. auriculus. This may indicate that competitive selection acts more on M. evotis. At sympatric localities, M. evotis displayed a shift to a more specialized trophic state with a trophic architecture (more highly placed articular process and robust molars) likely better at capturing beetles, whereas M. auriculus may have a greater advantage for capturing soft-bodied prey such as moths. On the other hand, the articular process is located lower relative to the toothrow of the dentary in M. auriculus. Also the shape of the jaw in this species suggests a weaker bite, more shearing force, and wider gape. All shape differences in jaw morphology are emphasized in sympatry, confirming active competitive interactions between these 2 species.

We investigated the diets of insectivorous bats (Chiroptera: Vespertilionidae) in forests with high densities of western spruce budworm (Choristoneura occidentalis, Lepidoptera: Tortricidae), in southern interior British Columbia, Canada. Caterpillars as potential prey were more common and widespread than previously reported. Caterpillar consumption by bats was more frequent where C. occidentalis larvae were more abundant, suggesting that the caterpillars being eaten were C. occidentalis. The frequency of caterpillar consumption was similar for Myotis evotis, which gleans prey from vegetation, and for other bat species that forage primarily by aerial-hawking. We suggest that caterpillars hanging by silk threads were captured by bats that foraged aerially.

I found Carios kelleyi Cooley & Kohls (formerly Ornithodoros kelleyi) (Acari: Ixodida: Argasidae) on five species of bats (Eptesicusfuscus, Myotis lucifugus, Myotis ciliolabrum, Myotis evotis, and Myotis volans) in the prairies of southeastern Alberta and north central Montana. This is the first occurrence of ticks on bats in Canada. This is also the first record of C. kelleyi on M. evotis and M. volans. Dates of parasitization ranged from 22 May to 17 October, and the number of ticks per host ranged from 1 to 44 (median two ticks per host). Number of parasitized individuals was significantly higher in rock-roosting E. fuscus compared with building-roosting E. fuscus, rock- and building-roosting M. lucifugus, and rock-roosting M. ciliolabrum and M. evotis. A significant sex bias was noted in rock-roosting E. fuscus in 2000 with significantly more females parasitized. The number of ticks per bat host was highest in 2001, corresponding to the driest and hottest summer of the survey.

Bat conservation is hindered by a lack of geographic-specific knowledge of characteristics of roost sites used by reproductive females. We examined roost selection by reproductive female Myotis evotis (long-eared myotis) in the Channeled Scablands of northeastern Washington. We used radiotelemetry to locate 35 roosts of reproductive female Myotis evotis. Habitat variables were measured for each roost itself and at a 0.1-ha microplot and 78-ha macroplot surrounding each roost. We measured habitat variables at random 0.1-ha microplots in the vicinity of each roost and at general random 0.1-ha microplots and 78-ha macroplots. Thirty-four roosts were found in crevices in small basalt rock formations. All radiomarked bats switched roosts at least once and roost switching apparently involved the entire colony. The average number of switches was 3.3 with an average of 2 days between roost switches. The distance traveled between day roosts averaged 148.9 m. Compared to random plots, roosts were in more open, rocky habitats, closer to edge of forest stands, and relatively distant from sources of permanent water.

We investigated the foraging behaviour of reproductive female long-eared bats, Myotis evotis, roosting solitarily in natural habitat in the badlands of the South Saskatchewan River valley, Alberta, Canada. Myotis evotis behaved differently than other temperate-zone insectivorous species studied previously. Individuals foraged all night, every night, regardless of ambient temperature or reproductive condition, and only spent a small proportion of the night roosting (less than 10% of the time spent out of the roost). A high daily energy demand and an energetically costly mode of flight may necessitate this behaviour. The ability to both aerial-hawk and glean prey from surfaces may make night-long foraging profitable for M. evotis, and for other flying nocturnal insectivores that can glean.

Summary 1 Most studies of the thermoregulatory ecology of bats have been limited to laboratory experiments or studies of individuals roosting in artificial structures. 2 We investigated the interaction between thermoregulatory behaviour and roost choice in reproductive female Western Long-Eared Bats, Myotis evotis (H. Allen), roosting solitarily in natural rock crevices. The study was conducted in the badlands of the South Saskatchewan River Valley, Alberta, Canada, during 1997 and 1998. 3 Individuals used torpor every day and the amount of time spent in torpor was primarily influenced by the amount of time available to do so. Minimum body temperature was influenced by ambient temperature, although the form of this relationship differed between pregnant and lactating females. Pregnant females used deep torpor more frequently than lactating females. 4 All individuals roosted in rock crevices but pregnant and lactating females chose roosts that were different in structure and thermal characteristics. Pregnant females chose horizontal roosts that cooled at night but warmed quickly during the day, thus allowing passive rewarming from torpor. Lactating females chose vertical roosts that stayed warm at night when non-volant pups were present, thereby minimizing thermoregulatory costs to the young. 5 The behaviours observed are adaptive, but differ from those of other temperate-zone insectivorous bats that have been studied in the past. This highlights the importance of studying free-ranging animals living in natural habitat if we are to have an accurate view of thermoregulatory strategies and the importance of roost characteristics for roost-site selection.

We used radiotelemetry to examine the roost-site preferences of four species of tree-roosting bats (Eptesicus fuscus, Lasionycteris noctivagans, Myotis evotis, and M. volans) in southern British Columbia, Canada, by radio-tracking bats to their day roosts. We found a total of 21 roost trees: 14 roosts were beneath loose bark, 5 were in cavities excavated by woodpeckers, and 2 were in natural cavities. Entrance height increased with tree height, but roost entrances tended to be situated below the level of the canopy. Of the 22 tree and site variables examined, only 3 significantly discriminated between roost trees and available trees: tree height, distance to the nearest available tree, and percent canopy closure. Bats preferred tall trees associated with low percent canopy closure and a short distance to the nearest available tree. Bats roosted in western white pine, and to a lesser extent ponderosa pine and western larch, in intermediate stages of decay more often than would be expected at random. Bats switched roosts frequently. The distance between subsequent roost trees was short, suggesting a degree of fidelity to a particular group of trees or area of forest. The number of days of rain during the roosting period significantly influenced the number of days spent in a particular roost, and thus ambient conditions may restrict the frequency with which bats can switch roosts.

A substantial body of work exists describing timing of migration and hibernation among bats in eastern North America, but less is known about these events among bats inhabiting the Rocky Mountain region. Yellowstone National Park is a geothermally influenced landscape comprised of diverse habitats, creating the opportunity for unique behaviors to develop among local bat populations. We identified the timing of migration for the local bat community and determined if bats overwinter in Yellowstone. To accomplish this, we radiotracked 7 little brown myotis ( Myotis lucifugus ), 5 western long-eared myotis ( M. evotis ), 4 big brown bats ( Eptesicus fuscus ), 4 silver-haired bats ( Lasionycteris noctivagans ), and 1 western small-footed myotis ( M. ciliolabrum ) from August to September 2010 and September to October 2011. We also used acoustic detectors to record bat activity from November through April 2011–2014 and sampled abundance of nocturnal insects using black-light traps from 2011 to 2012. Although availability of insects declined rapidly during August and afterward, several bat species remained active throughout autumn and winter. Bat activity was recorded during all months, even during periods of extreme cold. Radiotagged big brown bats, little brown myotis, and western small-footed myotis remained active in the study area throughout October, after the 1st snowfall of the season. While data for activity patterns in late autumn and winter prevented an estimation of the onset of hibernation, spring emergence occurred in April despite persistence of winter conditions. These data provide insights into the migration and hibernation strategies of bat populations in the Rocky Mountains and highlight gaps in our understanding of seasonal changes in these species.

Growing evidence supports the idea that species can diverge in the presence of gene flow. However, most methods of phylogeny estimation do not consider this process, despite the fact that ignoring gene flow is known to bias phylogenetic inference. Furthermore, studies that do consider divergence-with-gene-flow typically do so by estimating rates of gene flow using a isolation-with-migration model (IM), rather than evaluating scenarios of gene flow (such as divergence-with-gene flow or secondary contact) that represent very different types of diversification. In this investigation, we aim to infer the recent phylogenetic history of a clade of western long-eared bats while evaluating a number of different models that parameterize gene flow in a variety of ways. We utilize PHRAPL, a new tool for phylogeographic model selection, to compare the fit of a broad set of demographic models that include divergence, migration, or both among Myotis evotis, $M$. thysanodes and M. keenii. A genomic data set consisting of 808 loci of ultraconserved elements was used to explore such models in three steps using an incremental design where each successive set was informed by, and thus more focused than, the previous set of models. Specifically, the three steps were to (i) assess whether gene flow should be modeled and identify the best topologies, (ii) infer directionality of migration using the best topologies, and (iii) estimate the timing of gene flow. The best model (AIC model weight ${\sim}0.98$) included two divergence events (($M$. evotis, $M$. thysanodes), M. keenii) accompanied by gene flow at the initial stages of divergence. These results provide a striking example of speciation-with-gene-flow in an evolutionary lineage. [Myotis bats; PHRAPL; P2C2M; phylogeographic model selection; speciation with gene flow.].

Myotis keenii and M. evotis are sympatric in coastal areas of British Columbia and Washington. Some individuals are morphologically intermediate and cannot be identified confidently. This has raised questions about the correct identification of specimens collected in the area of overlap and the systematic relationship of the two taxa. Multiple discriminant function analysis of 12 cranial and 5 body measurements demonstrated the presence of two morphological groups in the area. The results suggest morphological convergence of the two taxa in Washington and that a number of individuals from western Washington were morphometrically intermediate. The intermediates were provisionally interpreted as representing overlapping intraspecific variation rather than intergradation between the taxa. Analysis of molecular data is required to resolve the systematics of these taxa.

One hundred and sixty-nine bats belonging to 6 different species and collected from 4 ecological zones (aspen parkland, boreal forest, grassland, and montane) in Alberta, Canada, during 1988 and 1989 were examined for helminths. Forty bats were infected with the stomach nematode Longibucca lasiura McIntosh and Chitwood, 1934. Sample size, prevalence, and mean intensity (with range in parentheses) of L. lasiura for the 6 species of bat were as follows: Myotis lucifugus, N = 130, 27%, 39 (1–121); Myotis ciliolabrum, N = 10, 10%, 1; Eptesicus fuscus, N = 6, 33%, 12 (2–22); Lasionycteris noctivagans, N = 2, 100%, 22 (5–39). Myotis evotis (N = 9) and Lasiurus cinereus (N = 3) were not infected. Longibucca lasiura was found in bats from all ecological zones except the boreal forest. This parasite was found in bats active during summer (June to August) and in hibernating M. lucifugus collected in September and April.

The foraging and echolocation behaviour of Myotis evotis was investigated during substrate-gleaning and aerial-hawking attacks. Bats gleaned moths from both the ground and a bark-covered trellis, however, they were equally adept at capturing flying moths. The calls emitted by M. evotis during substrate-gleaning sequences were short, broadband, and frequency-modulated (FM). Three behavioural phases were identified: search, hover, and attack. Gleaning search calls were significantly longer in duration, lower in highest frequency, and larger in bandwidth than hover/attack calls. Calls were detected in only 68% of gleaning sequences, and when they were emitted, bats ceased calling approximately 200 ms before attacking. Terminal feeding buzzes, the rapid increase in pulse repetition rate associated with an attempted prey capture, were never recorded during gleaning attacks. The echolocation calls uttered by M. evotis during aerial-hawking foraging sequences were also short duration, high frequency, FM calls. Two distinct acoustic phases were identified: approach and terminal. Approach calls were significantly different from terminal calls in all variables measured. Calls were detected in 100% of aerial-hawking attacks and terminal feeding buzzes were invariably produced. Gleaning hover/attack calls were spectrally similar to aerial approach calls, but were shorter in duration and emitted at a significantly lower (but constant) repetition rate than aerial signals. Although the foraging environment (flight cage contents) remained unchanged between tasks (substrate-gleaning vs. aerial-hawking), bats emitted significantly lower amplitude calls while gleaning. We conclude that M. evotis adjusts its echolocation behaviour to meet the perceptual demands (acoustical constraints) imposed by each foraging situation.

Bats are reservoirs for many different coronaviruses (CoVs) as well as many other important zoonotic viruses. We sampled feces and/or anal swabs of 1,044 insectivorous bats of 2 families and 17 species from 21 different locations within Colorado from 2007 to 2009. We detected alphacoronavirus RNA in bats of 4 species: big brown bats (Eptesicus fuscus), 10% prevalence; long-legged bats (Myotis volans), 8% prevalence; little brown bats (Myotis lucifugus), 3% prevalence; and western long-eared bats (Myotis evotis), 2% prevalence. Overall, juvenile bats were twice as likely to be positive for CoV RNA as adult bats. At two of the rural sampling sites, CoV RNAs were detected in big brown and long-legged bats during the three sequential summers of this study. CoV RNA was detected in big brown bats in all five of the urban maternity roosts sampled throughout each of the periods tested. Individually tagged big brown bats that were positive for CoV RNA and later sampled again all became CoV RNA negative. Nucleotide sequences in the RdRp gene fell into 3 main clusters, all distinct from those of Old World bats. Similar nucleotide sequences were found in amplicons from gene 1b and the spike gene in both a big-brown and a long-legged bat, indicating that a CoV may be capable of infecting bats of different genera. These data suggest that ongoing evolution of CoVs in bats creates the possibility of a continued threat for emergence into hosts of other species. Alphacoronavirus RNA was detected at a high prevalence in big brown bats in roosts in close proximity to human habitations (10%) and known to have direct contact with people (19%), suggesting that significant potential opportunities exist for cross-species transmission of these viruses. Further CoV surveillance studies in bats throughout the Americas are warranted.

Myotis evotis (H. Allen, 1864). Smithson. Mise. Coll., 7:48. TYPE LOCALITY: USA, California, Monterey. DISTRIBUTION: S British Columbia, S Alberta, S Saskatchewan (Canada) to New Mexico (USA) and Baja California (Mexico). SYNONYMS: chrysonotus, micronyx, pacificus. COMMENTS: Subgenus Myotis. See Genoways and Jones (1969fe:l). See Manning and Jones (1989, Mammalian Species, 329)., Published as part of Karl F. Koopman, 1993, Order Chiroptera, pp. 137-241 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 210, DOI: 10.5281/zenodo.7353060, {"references":["Manning, R. W., and J. K. Jones, Jr. 1989. Myotis evotis. Mammalian Species, 329: 1 - 5."]}

1. Most studies examining interactions between insectivorous bats and tympanate prey use the echolocation calls of aerially-feeding bats in their analyses. We examined the auditory responses of noctuid (Eurois astricta) and notodontid (Pheosia rimosa) moth to the echolocation call characteristics of a gleaning insectivorous bat, Myotis evotis. 2. While gleaning, M. Evotis used short duration (mean ± SD = 0.66 ± 0.28 ms, Table 2), high frequency, FM calls (FM sweep = 80 − 37 kHz) of relatively low intensity (77.3 + 2.9, −4.2 dB SPL). Call peak frequency was 52.2 kHz with most of the energy above 50 kHz (Fig. 1). 3. Echolocation was not required for prey detection or capture as calls were emitted during only 50% of hovers and 59% of attacks. When echolocation was used, bats ceased calling 324.7 (±200.4) ms before attacking (Fig. 2), probably using prey-generated sounds to locate fluttering moths. Mean call repetition rate during gleaning attacks was 21.7 (±15.5) calls/s and feeding buzzes were never recorded. 4. Eurois astricta and P. rimosa are typical of most tympanate moths having ears with BFs between 20 and 40 kHz (Fig. 3); apparently tuned to the echolocation calls of aerially-feeding bats. The ears of both species respond poorly to the high frequency, short duration, faint stimuli representing the echolocation calls of gleaning M. evotis (Figs. 4–6). 5. Our results demonstrate that tympanate moths, and potentially other nocturnal insects, are unable to detect the echolocation calls typical of gleaning bats and thus are particularly susceptible to predation.

Roosts are a critical habitat component for bats and may influence their survival and fitness. We used radiotelemetry to investigate characteristics of day-roosts of female long-eared myotis (Myotis evotis) in watersheds characterized by different forest conditions and the spatial relationships between day-roosts and available water. We tracked 21 bats to 73 roosts (n = 102 occasions) from June to August 1996 and 1997 on the western slope of the Cascade Mountains, Oregon. Bats primarily used conifer stumps as day-roosts in watersheds dominated by younger forests and used conifer snags, and to a lesser extent conifer stumps, in watersheds with greater proportions of older forests. Individual long-eared myotis used different types of structures as day-roosts, and type of structure used did not differ with reproductive condition. Day-roosts were primarily located in upslope habitat and averaged 0.59 ± 0.03 km from available water and 0.66 ± 0.02 km from capture sites. Roosts were not located closer to available water than random points, but were closer than random points to captures sites. Conifer snags used as day-roosts averaged 34 ± 5 m in height and 93 ± 12 cm diameter at breast height (dbh); snags in intermediate stages of decay had highest use. Use of conifer snags was positively associated with the number of snags within 20 m and negatively associated with distance from stand edge. Conifer stumps used as day-roosts averaged 133 ± 9 cm in height and 59 ± 4 cm dbh. Western hemlock and Douglas-fir stumps were used more often than western redcedar stumps as day-roosts. Odds of a stump being used as a day-roost increased with increasing height of the stump (downhill side) and whether it was situated in a gap in vegetation. We contend that management of day-roosts for forest-dwelling bats should focus on maintaining large conifer snags across landscapes through space and time. In landscapes where there are relatively few large conifer snags, stumps appear to provide important, but ephemeral, roosts for long-eared myotis.

Twenty species of bats (Molossidae, Vespertilionidae) were collected from California, New Mexico, Oregon, South Carolina, Utah, and Baja California Norte (Mexico), and 29 of 404 (7%) animals, including Antrozous pallidus, Eptesicus fuscus, Myotis auriculus, Myotis californicus, Myotis ciliolabrum, Myotis evotis, Myotis lucifugus, Myotis thysanodes, Myotis vivesi, Myotis volans, Myotis yumanensis, and Nycticeius humeralis were infected with Eimeria spp., which represent 6 new species. Sporulated oocysts of a new species from A. pallidus are subspheroidal, 24.8 x 21.6 (22-27 x 19-24) microm with a polar granule and a large globular residuum. The oocyst wall is sculptured, with 2 layers, approximately 1.5 thick. Ovoidal sporocysts are 11.5 x 7.8 (9-13 x 7-10) microm, with Stieda body and residuum of many large granules. Sporulated oocysts of a new species from M. californicus are subspheroidal, 20.7 x 18.2 (19-23 x 16-20) microm, with 1-7 tiny polar granules, but without oocyst residuum. The oocyst wall is rough, with 2 layers, approximately 1.4 thick. Ovoidal sporocysts are 11.2 x 7.3 (10-12 x 7-8) microm, with Stieda body and a globular residuum. Sporulated oocysts of a second new species from M. californicus are subspheroidal, 23.1 x 20.7 (20-26 x 19-23) microm, with residuum and 1 polar granule, but a micropyle is absent. The oocyst wall is rough with 2 layers, approximately 1.5 thick. Ovoidal sporocysts are 12.5 x 7.2 (11-14 x 7-8) microm, with a Stieda body and residuum. Sporulated oocysts of a new species from M. ciliolabrum are subspheroidal, 24.9 x 20.1 (18-27 x 17-23) microm, with 1-2 polar granules, but without micropyle and residuum. The oocyst wall is rough with 2 layers, approximately 1.5 thick. Ellipsoidal sporocysts are 12.5 x 9.0 (8-14 x 7-10) microm, with Stieda and substieda bodies and residuum. Sporulated oocysts of a new species from M. evotis are subspheroidal, 21.3 x 18.6 (20-24 x 15-20) microm, with a prominent polar granule, but without micropyle and residuum. The oocyst wall is smooth with 2 layers, approximately 1.0 thick. Ovoidal sporocysts are 12.2 x 8.0 (11-13 x 7.5-9) microm, with Stieda and substieda bodies and residuum. Sporulated oocysts of the new species from N. humeralis are subspheroidal, 22.4 x 18 (21-24 x 17-20) microm, with 1-3 polar granules, but residuum and micropyle are absent. The oocyst wall is lightly sculptured with 2 layers, approximately 1.4 thick. Ovoidal sporocysts are 10.9 x 7.7 (9-12 x 6-8) microm, with Stieda body and residuum. Sporulated oocysts of E. pilarensis Scott and Duszynski, 1997 and those of at least 12 other morphological forms were seen in the other infected bats; these latter forms were seen in too few numbers to be adequately described as new species.

(1) The morphology, echolocation calls, foraging behaviour and prey distribution of two temperate zone species of insectivorous bats was studied to assess the hypothesis that sexual differences in distribution pattern are the result of differences in energy demand. (2) In an area of the eastern slopes of the Rocky Mountains (Canada) characterized by low ambient temperatures and low insect abundance, over 90%yo of the Myotis lucifugus caught during the summer were adult males while an equal sex ratio of Myotis evotis was caught. (3) M. lucifugus forage low over water on aerial prey, especially chironomids, which are abundant only for a short time after sunset. (4) M. evotis forage along paths and in forest and prey primarily on moths. They take insects from the air but laboratory studies indicate that they are also adept at gleaning prey from the ground and vegetation. This provides a broader, more predictable food resource than is available to M. lucifugus. (5) I suggest that the flexible foraging strategy of M. evotis allows reproductive females, with their high energy demand, to inhabit areas that cannot support reproductive female M. lucifugus. Males of both species can exist in such areas because of lower energy demand and, potentially, the use of torpor under adverse conditions. Selecting such areas and reducing foraging time may benefit males if there are risks incurred while they forage.

Winter records of bats in the Pacific Northwest are extremely limited (Barbour and Davis 1969). Of the 15 bat species other than Plecotus townsendii in Oregon and Washington, at least two are considered migratory. Five species (Eptesicus fuscus, Myotis californicus, M. Iucifugus, M. volans, Antrozous pallidus) are known to hibernate in the eastern portion of their ranges (Barbour and Davis 1969; Twente 1960). Marcot (1984) reported records for hibernating Myotis evotis in northern California, Senger et al. (1974) noted five species of hibernating myotids (M. californicus, M. evotis, M. Iucifugus, M. volans and M. yumanensis) in Washington, Genter (1986) observed hibernating M. Ie.;bii in Idaho, and Jewett (1955) recorded Tadarida brasiliensis from buildings in southwestern Oregon. Most hibernacula contained relatively few bats (range = 1-41) when compared with those of the eastern United States (Barbour and Davis 1969). The reports were from studies concentrated in small geographical areas and involved a small number of caves. Twente (1960), who investigated over 600 potential hibernacula in Utah, speculated few hibernating bats were noted because of warm temperatures in the caves. Results of Genter (1986), Marcot (1984), and Senger et al. (1974) suggest that hibernacula in the Pacific Northwest may contain larger bat populations than reported by Twente (1960). This prompted us to conduct a more extensive search that included most of Oregon and Washington. We defined winter as the period from 1 November to 1 April. During winters of 1982-1989, we searched more than 650 caves and mines and 70 buildings in Oregon and Washington. Seven of the caves were previously surveyed by Senger et al. (1974). Most bats were easily identified from observable external characters (Hall 1981). Closely related species (M. Iucifugus, M. yomRnensis; and M. thysanodes, M. evotis) were collected if positive identification could not be made in the field. In addition, we obtained winter records of museum specimens collected in Oregon and Washington from American Museum of Natural History (AMNH), the National Museum (USNM), the University of Puget Sound (PSMNH), the University of Washington (UW), Southern Oregon State College (SOSC), the San Diego Museum of Natural History (SDMNH), Oregon State University (OSUFW), the University of Michigan (UMMZ), and Walla Walla College (WWC). We located 174 bats of seven species at 26 sites (Table 1). M. volans (124) and M. Ieibii (36) were encountered more than any other species. Numbers of bats were

Jaw and skull morphologies were analyzed in two morphologically distinct species of bats, Myotis evotis (substrate gleaner) and Myotis volans (aerial insectivore). Force vector analyses were performed on five major muscle-bone lever systems to compare the relative adductive forces produced at three functional points (the incisors, canines, and protoconids of the lower second molar) during jaw closure. Relative force produced by contraction of a given adductor was approximated using a modified muscle mass value. Seven angles of dentary position were analyzed for changes in mechanical advantage due to changing muscle fiber orientation. Results of the analyses suggest that M. evotis has a more forceful bite than M. volans , but only as the upswinging dentary approaches closure. Moreover, M. evotis has the potential for a quicker jaw closure than M. volans and the ability to produce series of rapid nipping motions. The masticatory apparatus of M. volans appears well suited for capture of insect prey using a wide gape followed by a forceful closure. These results are interpreted in view of available ecological data concerning the foraging behavior of the two species.

Two extremely similar insectivorous bats, Myotis evotis and M. auriculas , differ in food preferences when sympatric (Black, 1974). Myotis auriculus preys generally upon moths and some beetles, whereas M. evotis specializes on beetles. Does this specialization of M. evotis persist in allopatry, indicating that it has evolved as a food specialist, or in the absence of its close competitor, does it eat both moths and beetles without a strong preference? What sort of effect, if any, does M. evotis exert on the diet of M. auriculus in areas of sympatry? Both species were captured in areas of allopatry during the summer of 1972. Fecal samples were collected and analyzed using Black's (1974) technique. My results indicate that when in allopatry, M. evotis and M. auriculus have similar food habits. Thus, in sympatry, competition for food is avoided by changes in food preferences of M. evotis . Furthermore, each species exhibits sexual differences in foods taken in areas of allopatry, indicating that intraspecific niche subdivision occurs in each of these bats only in the absence of the potential competitor.