Search

Little information exists on the habitat use and feeding ecology of insectivorous bats in arid ecosystems, especially at and near uranium mines in northern Arizona, within the Grand Canyon watershed. In 2015–2016, we conducted mist-netting, nightly acoustic monitoring (>1 year), and diet analyses of bats, as well as insect sampling, at 2 uranium mines (Pinenut and Arizona 1) with water containment ponds. Because of physical barriers and limited general access to areas within the mine yard, mist-netting was limited to outside of the perimeter fence and away from the containment ponds. Mist-netting also occurred at 2 nearby sites that served as proxies to the mines. Bats captured directly at the mines included one pregnant Antrozous pallidus and 3 adult male Parastrellus hesperus. At the proxy sites, we captured 45 individuals identified as A. pallidus, Corynorhinus townsendii, Eptesicus fuscus, Euderma maculatum, Lasionycteris noctivagans, Myotis californicus, Myotis ciliolabrum, P. hesperus, and Tadarida brasiliensis. The nightly and seasonal presence of bats, as shown through acoustic recordings at each mine, coincided with the seasonal migratory and hibernation behaviors of the bat species. Statistical comparisons of acoustic recordings with precipitation data collected over one year show that seasonal monsoon rains generally had a negative effect on the nightly activity and presence of bats. Diets of P. hesperus from both mines were comprised mostly of coleopterans but also included smaller volumes of Hymenoptera, Hemiptera, Lepidoptera, Diptera, and Neuroptera. The diet of A. pallidus was comprised solely of Coleoptera. Diets of bat species from the proxy sites were characteristic of their known feeding ecology, which ranged from the consumption of soft-bodied insects (e.g., moths) by C. townsendii to the consumption of hard-bodied insects (e.g., beetles) by E. fuscus. Ultimately, the increased knowledge of the natural history of bats through multiple methods of data collection allows for a better understanding of complex arid ecosystems. It also provides resources needed for the management of habitat associated with alternative energy, such as uranium mining.

Climate change is predicted to create increasingly arid deserts with fewer and smaller water sources. Because free water is already limiting for arid-adapted animals, reductions in water likely will impact desert species and how they compete for this limited resource. Our objective was to examine how the size of water sources influenced competition between 2 ecologically similar bats, Parastrellus hesperus and Myotis californicus, in the American Southwest. Bats are a highly successful taxon in deserts, although many rely upon access to free water. We examined bat activity observationally over 35 different-sized water sources throughout the Mojave Desert in southwestern Utah, United States, and experimentally reduced the surface area of 2 water sources. Parastrellus hesperus and M. californicus typically occurred at the same water sources, but both species temporally partitioned their use of shared water sources regardless of the surface area of the water. Experimentally reducing surface area of water sources negatively affected drinking behaviors of both species and resulted in higher overall activity, but temporal partitioning still occurred. While loss of water may influence some competitive interactions, mechanisms such as temporal partitioning can potentially allow continued co-use of limited resources by competing species.

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)...

The California myotis (Myotis californicus) and the western small-footed myotis (Myotis ciliolabrum) are largely sympatric in western North America, and are especially similar morphologically such that only subtle features of their skull distinguish the two species. Previous analysis of mitochondrial DNA (mtDNA) sequence data resulted in paraphyly of these two species. Our objective was to examine genetic differences in nuclear loci between M. californicus and M. ciliolabrum, investigate their relationship with M. leibii, and to address the conflicting morphological and mtDNA data sets. We analyzed 198 amplified fragment length polymorphism (AFLP) fragments from 17 M. californicus, 16 M. ciliolabrum, and 10 M. leibii using principal coordinate (PCoA), neighbor-joining, Bayesian, and parsimony analyses. Our analyses recovered well-supported separation of M. californicus and M. ciliolabrum based on nuclear markers, suggesting the failure of the mitochondrial markers to recover monophyletic lineages was due to a lack of lineage sorting. Unexpectedly, M. ciliolabrum was paraphyletic with respect to M. leibii individuals from the eastern United States. In conclusion, our analysis of nuclear AFLP markers recovered distinct genetic lineages or clusters that corresponded to the recognized species defined by morphology, M. californicus, M. ciliolabrum, and M. leibii. We propose that these divergences are somewhat incomplete and the divergence between M. ciliolabrum and M. leibii occurred more recently than the speciation events separating the currently sympatric species M. californicus and M. ciliolabrum.

We recorded for the first time the species Rhogeessa alleni in the state of Hidalgo, Mexico, and registered the third locality for Myotis californicus. The bats were caught between March 2010 and September 2012. Specimens were preserved in skin, skull, and parts of skeleton and were deposited at the Coleccion Mastozoologica of Centro de Investigaciones Biologicas, Universidad Autonoma del Estado de Hidalgo. We provide external and cranial measurements as well as information about reproductive condition and habitat of each specimen.

Bats have been observed to shift the frequency of their echolocation calls in the presence of other echolocating bats, ostensibly as a way to reduce acoustic interference. Few studies, however, have examined the theoretical efficacy of such jamming avoidance responses. The present study uses the wideband ambiguity function to analyze the effects of acoustic interference from conspecifics and congeneric heterospecifics on the target acquisition ability of Myotis californicus and Myotis yumanensis, specifically whether unilateral or bilateral frequency shifts reduce the effects of such interference. Model results suggest that in conspecific interactions, M. yumanensis recovers its target acquisition ability more completely and with less absolute frequency shift than does M. californicus, but that alternative methods of jamming avoidance may be easier to implement. The optimal strategy for reducing heterospecific interference is for M. californicus to downshift its call and M. yumanensis to upshift its call, which exaggerates a preexisting difference in mean frequency between the calls of the two species. Further empirical research would elucidate whether these species do in practice actively employ frequency shifting or other means for jamming avoidance, as well as illuminate the role of acoustic interference in niche partitioning.

Se presenta la lista actualizada de los mamíferos del Parque Nacional El Chico con base en el trabajo de campo realizado entre los años 2004 y 2006. Se identificaron 30 especies, 13 de ellas se registran por primera vez en el parque: Glaucomys volans, Peromyscus melanotis, Reithrodontomys megalotis, R. sumichrasti, Spilogale gracilis, Cryptotis mexicana, Sorex saussurei, Dermanura azteca, Corynorhinus towsendii, Eptesicus fuscus, Lasiurus cinereus, Myotis californicus y M. velifer. El orden mejor representado, con 10 especies (33.33 %) fue Rodentia, seguido por Carnivora con ocho especies (26.67 %). El 16.67 % de las especies están consideradas en estado de conservación delicado (C. mexicana, S. saussurei, Sciurus oculatus, G. volans y Corynorhinus mexicanus). Localmente las amenazas para la mastofauna son consecuencia de los asentamientos humanos y el turismo descontrolado. El Chico es importante para la conservación y manejo de los mamíferos de Hidalgo, porque en el habita el 23.8 % de la mastofauna estatal, no obstante su reducida extensión territorial (2,739 ha).

During a 2-year study, we documented eight species of bats using bridges in the lower Rio Grande Valley of New Mexico. Of 17 bridges surveyed, 15 (88%) contained day-roosting bats and ≥8 bridges (47%) contained maternity colonies with one or more species, including the Arizona myotis (Myotis occultus), Yuma myotis (Myotis yumanensis), and Brazilian free-tailed bat (Tadarida brasiliensis). The pallid bat (Antrozous pallidus), big brown bat (Eptesicus fuscus), silver-haired bat (Lasionycteris noctivagans), California myotis (Myotis californicus), and fringed myotis (Myotis thysanodes) roosted infrequently in bridges. Use of bridges by day-roosting bats differed seasonally, with most individuals occupying bridges April–October. During November–March, relatively few individuals of only three species (L. noctivagans, M. yumanensis, and T. brasiliensis) occupied bridges. Individuals roosted at many sites in bridges, but 99.9% roosted in narrow cracks and crevices. A total of 36,629 day-roosting bats wa...

Aim The influence of landscape structure on the distribution patterns of bats remains poorly understood for many species. This study investigates the relationship between area and isolation of islands and the probability of occurrence of six bat species to determine whether persistence and immigration abilities vary among bat species and foraging guilds. Location Thirty-two islands in the Gulf of California near the Baja California peninsula in north-west Mexico. Methods Using logistic regression and Akaike information criterion (AIC) model selection, we compared five a priori models for each of six bat species to explain patterns of island occupancy, including random patterns, minimum area effects, maximum isolation effects, additive area and isolation effects and compensatory area and isolation effects. Results Five species of insectivorous bats ( Pipistrellus hesperus , Myotis californicus , Macrotus californicus , Antrozous pallidus and Mormoops megalophylla ) displayed minimum area thresholds on incidence. The probability of occurrence tended to decrease at moderate distances of isolation ( c . 10 ‐15 km) for these species (excepting A. pallidus ). The distributions of two non-insectivorous species ( Leptonycteris curasoae and Myotis vivesi ) were not influenced by island size and isolation. Main conclusions Minimum area thresholds on incidence suggest that island occupancy by insectivorous bats may be limited by resource requirements. Islands smaller than 100 ha typically did not support occupancy or use by insectivorous bats, except at minimal isolation distances. Insectivorous bat species may also be more sensitive to moderate levels of habitat isolation in some landscape contexts than previously expected. Our results suggest that differences in foraging habits may have important implications for understanding the distribution patterns of bats.

During colder months in temperate regions, non-migratory bats are suspected to remain relatively inactive during hibernation. I examined activity of bats November–March in a region of North America with moderate winter temperatures. Bats were captured in nets over water and along flyways in southern and central New Mexico. In 47 nights, I captured 401 individuals representing 12 species. Captures for 10 species represent records of bats previously unknown outside roosts during colder months in New Mexico. The western pipistrelle (Pipistrellus hesperus), silver-haired bat (Lasionycteris noctivagans), California myotis (Myotis californicus), pallid bat (Antrozous pallidus), and Brazilian free-tailed bat (Tadarida brasiliensis) were captured frequently, whereas the western small-footed myotis (M. ciliolabrum), Townsend's big-eared bat (Corynorhinus townsendii), big brown bat (Eptesicus fuscus), Allen's big-eared bat (Idionycteris phyllotis), hoary bat (Lasiurus cinereus), fringed myotis (M. thysanod...

We examined intra- and interspecific patterns of roost-site selection by females of three species of forest-dwelling bats (silver-haired, Lasionycteris noctivagans; big brown, Eptesicus fuscus; and California, Myotis californicus) in the Pend d’Oreille Valley in southern British Columbia. Roost-sites were located by outfitting reproductive and non-reproductive female bats with radio-transmitters and tracking them during the daytime. The tree and site characteristics of roost trees used by each bat species were then compared to those of randomly available trees with cavities, as well as to each other, using logistic regression. All three bat species selected roosts that were taller than cavity trees, and the majority of roost trees were emergent or canopy trees. In addition, tree species and the type of cavity were important predictors of whether trees were used as roosts in both intra- and interspecific analyses. The majority of silver-haired and big brown bat roost trees were in hollows in live trembling aspen trees (Populus tremuloides), but both species used small numbers of roosts on conifer snags. In contrast, the majority of California bat roosts were beneath loose bark on conifer snags, particularly Douglas-fir (Pseudotsuga menziesii), in intermediate stages of decay. In general, site characteristics were only weak predictors of differences between roost and random trees, and roost trees used by the three bat species, but roost trees were found in patches with lower percent canopy closure and greater density of available trees. These results suggest that while all three species of forest-dwelling bats use large trees, within this restricted range of trees there is considerable variation among species in the types of cavities and the tree species used. Maintaining stands containing mature trembling aspen is necessary to provide silver-haired and big brown bats with suitable roosting opportunities, but to meet the needs of California bats, areas rich in conifer snags must be protected. Thus, unique management strategies or silvicultural practices may be required to maintain suitable habitat for all bat species in a given area.

Nine bats, 3 Tadarida brasiliensis mexicana, and 6 Myotis californicus, collected from 2 locations in Northern California between September 1968 and April 1969 were found to harbor 4 species of digeneans: Plagiorchis vespertelionis, Paralecithodendrium carlsbadensis, Paralecithodendrium transversum, and Paralecithodendrium Swansoni. These findings represent new locality records for all and a new host record for P. transversum.

The California myotis, Myotis californicus, and western small-footed myotis, Myotis ciliolabrum, are 2 morphologically similar bats which have had a complex taxonomic history due to intraspecific geographic variation across their sympatric distribution in western North America. Despite several published differences, field identification remains problematic in the southwestern United States. Mitochondrial cytochrome-b and control region fragments were amplified from tissue samples (n ¼ 20) from Texas, Oklahoma, New Mexico, Arizona, Utah, and California to examine species boundaries and phylogenetic relationships. DNA sequences (1,184 bp) were used in parsimony and maximum-likelihood analyses. To corroborate species identification, cranial measurements from all specimens included in the molecular analysis along with additional specimens were analyzed statistically using principal components analysis (PCA). Individuals were designated either as M. californicus or M. ciliolabrum. Molecular analysis placed M. leibii within clades containing both M. californicus and M. ciliolabrum. In addition, sequence divergence and phylogenetic results do not recover distinct lineages for each species (M. californicus and M. ciliolabrum) as recognized by morphology. Our results suggest that these species have recently diverged, or alternatively that they are 1 phenotypically variable species. Based on network estimation of cytochrome-b haplotypes, phylogeographic structure is minimally represented between haplotypes with an east-west separation in the southwestern United States.

To document year-to-year reuse of roost trees by forest-dwelling bats we monitored trees in southern British Columbia that we first identified as maternity roosts of California bats (Myotis californicus) in 1995. Initially we identified roost trees by tracking radio-tagged individuals. Then we revisited each tree in subsequent years up to 2000. At the start of the study the bats roosted under loose bark or in cavities in dead trees. Seven of eight trees were still standing in 2000, although all had lost bark since 1995, particularly ponderosa pines (Pinus ponderosa). In 1995, after radio-tagged bats had moved and the tags had fallen off, trees either were occupied by colonies of 5 to 52 M. californicus or they were unoccupied. In contrast, roost counts in subsequent years indicated that colonies rarely used the same trees and most observations were of one or two bats. Thus, while bats continued to use most of the trees over the 5 y period, the numbers of individuals declined and much of the use m...

Histoplasma capsulatum was isolated from gut, lung, liver, and spleen of 17 of 208 captured bats belonging to 6 different genera and species. Three of the 17 infected bats were from the State of Guerrero and 14 were from the State of Morelos. All were adult bats: 6 males (1 Pteronotus parnellii, 2 Natalus stramineus, 2 Artibeus hirsutus, and 1 Leptonycteris nivalis) and 11 females (1 Myotis californicus, 1 Mormoops megalophylla, 8 A. hirsutus, and 1 L. nivalis). High rates of bat infection with H. capsulatum were found in the monitored sites of the State of Morelos. Histoplasma infection of N. stramineus, A. hirsutus, and L. nivalis should be considered as the first records in the world. The fungus isolated from infected bats was identified by its typical mycelial-phase morphology and by its yeast-phase conversion. Exoantigen production confirmed the fungal identification by the presence of specific precipitation lines in double immunodiffusion assays using human immune serum. Histopathologic studies showed intracellular yeast-like cells compatible with H. capsulatum yeast-phase in tissues of several bats, especially in pulmonary (intra-alveolar and septal) macrophages, with none or minimal tissue reaction. In contrast to past reports, present data support a high risk of bat infection with H. capsulatum in Mexican cave environments.

The wintering strategies of many species of bats in the Pacific Northwest are poorly understood (Barbour and Davis 1969; Kunz 1982). Although Silver-haired Bats (Lasionycteris noctivagans) and California Myotis (Myotis californicus) have been observed wintering in Washington State and British Columbia (Nagorsen and others 1993), the specifics of their wintering behaviors and distributions in the region are unclear. Silver-haired Bats are presumed to migrate south to warmer regions during winter (Izor 1979), although limited evidence suggests this species may not be as migratory in the Pacific Northwest as elsewhere (Schowalter and others 1978; Kunz 1982; Cryan 2003). The few observations of winter roosts used by Silverhaired Bats in the Pacific Northwest mostly involved solitary bats found in trees (Cowan 1933; Nagorsen and others 1993). California Myotis are presumed to hibernate through the winter and generally remain dormant in caves, mines, buildings or tree cavities within several hundred kilometers of their summer habitat

The observation of a perceived 4-mm tail extension beyond the border of the interfemoral membrane of the western small-footed myotis, Myotis ciliolabrum , and the absence of the free tail in the California myotis, Myotis californicus , stimulated a quantitative study to determine if the tail character could be verified as a consistent external criterion to differentiate these similar species. Existing study skins were unsuitable for this purpose, because the tail character had been destroyed or distorted by replacement of the tail vertebrae with wire. Twenty-three ciliolabrum and 22 californicus were collected in the Mojave Desert of California and prepared as study skins with tail vertebrae in situ. Examination of these specimens, identified by conventional methods, confirmed that the exserted tail was characteristic of ciliolabrum . Original descriptions, usually based on specimens preserved in alcohol, indicated that the tail character was recognized in ciliolabrum over a century ago.

We followed nine radiotagged female California bats ( Myotis californicus ) to 19 roosts in trees at two study sites in southcentral British Columbia. Bats regularly switched roosts and the number of bats emerging from known roosts fluctuated widely. Logistic-regression analysis showed that reproductively active females preferred trees further away from other trees of the same height or greater, and closer to neighboring trees, relative to available trees in the immediate vicinity of the roost. Diameter at breast height and distance to the nearest tree of the same or greater height explained significant proportions of the variation between roost and available trees found in other areas of the same forest stand. Roost trees had significantly larger diameters and were further away from trees of the same or greater height. Percentage of canopy closure also explained a significant proportion of the variation between roost and available trees, such that roost trees were situated in areas with lower canopy closure than available trees in other areas of the same stand. Roost and available trees were classified correctly >70% of the time based on the above tree characteristics. However, roost trees were only correctly classified 39% of the time in the analysis of site characteristics. Our results, combined with those from other recent studies, lead to the general hypothesis that forest-roosting bats require a number of large dead trees of specific species, in specific stages of decay, and that project above the canopy in relatively open areas. For management and conservation reasons, there should be a strong incentive to evaluate this hypothesis for a variety of species in a variety of locations to test its generality.

Se aporta información sobre la distribución, hábitat, medidas y condición reproductiva de nueve especies de murciélagos del estado de Guerrero, México. Cuatro especies representan el segundo registro para el estado (Choeroniscus godmani, Myotis auriculus apache, Myotis thysanodes aztecus y Nyctinomops femorosaccus), tres representan el tercer registro (Musonycteris harrisoni, Chiroderma salvini scopaeum y Enchisthenes hartii), y dos son el cuarto registro (Hylonycteris underwoodi minor y Myotis californicus mexicanus).

Background: Molecular characterization of rabies virus has been used to trace spillover transmission from reservoir species to non-reservoir animals and humans (molecular epidemiology), and to monitor emergence of specific strains of the virus into new species and geographic areas (molecular surveillance). Objectives: To characterize the enzootic strains of rabies virus in California wildlife for epidemiological investigation of transmission to non-reservoir animals and humans. Study design: Molecular characterization was performed on rabies strains from 213 bats, 276 terrestrial animals and one human case, by RT-PCR amplification of the viral nucleocapsid (N) gene followed by Dde I digestion and restriction endonuclease analysis (REA). Brain material from 88 terrestrial animals and 74 bats was stained with a panel of 20 monoclonal antibodies (MABs) directed against the N protein. In order to characterize rabies from very small quantities of brain tissue a nested RT-PCR was developed and evaluated for sensitivity of rabies detection. Results and Conclusions: Enzootic terrestrial rabies in California is confined to the Central Valley, the western slope of the Sierra Nevada, and the Central and Northern Pacific Coast Ranges. No terrestrial reservoirs were identified south of the Tehachapi Mountains or east of the Sierra Nevada. Bat strains accounted for rabies in terrestrial animals in these regions. Among terrestrial rabies strains REA identified ten genotypes that segregated geographically and were associated with skunk and fox populations from distinct locations. Co-circulation of three genotypes occurred in Placer County, which had the highest incidence of rabies in skunks. In regions with terrestrial enzootic rabies, the strain from that region accounted for 73% of spillover cases. Bat strains accounted for the remaining 27%. Among terrestrial animals MABs identified three predominant patterns. In rabies strains from bats REA identified ten major and two minor patterns primarily associated with genus and species of bat. Sharing of strains between species was observed. An additional sixteen unclassified REA bat patterns were observed in only one or two individuals of various species. MABs identified four major patterns in bats associated with genus and species of bat with considerable variability. The bat strains most frequently detected in spillover cases throughout California were from the California myotis ( Myotis californicus ) and Mexican free-tailed bat ( Tadarida brasiliensis ). Nested RT-PCR increased the detection level of rabies virus 100 000-fold, to 0.03 TCID 50

In 1995, a three-year study was initiated to assess the current status of bat species of concern, elucidate distribution and relative abundance, and obtain information on roosting sites of bats. The authors captured and released 1532 bats of 15 species (Myotis californicus, M. ciliolabrum, M. evotis, M. thysanodes, M. volans, M. yumanensis, Lasiurus cinereus, Lasionycteris noctivagans, Pipistrellus hesperus, Eptesicus fuscus, Euderma maculatum, Corynorhinus townsendii, Antrozous pallidus, Tadarida brasiliensis, and Nyctinomops macrotis) and followed 32 bats of eight species (M. evotis, M. thysanodes, M. volans, E. fuscus, E. maculatum, C. townsendii, A. pallidus, and N. macrotis) to 51 active diurnal roosts. The most abundant species were L. noctivagans, E. fuscus, L. cinereus, M. evotis, M. volans, and M. ciliolabrum. Most of these species are typical inhabitants of ponderosa pine-mixed coniferous forests.

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.

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

1. 1. Nine of eleven species of desert bats tested demonstrated the ability to initiate and maintain flight at reduced body temperatures. This ability is associated with periodic activity throughout the winter. 2. 2. Of the two species studied most intensively, Pipistrellus hesperus demonstrated a stronger relationship between ambient and body temperatures than did Myotis californicus . It is hypothesized that differences in total body insulation are responsible for the difference in this relationship. 3. 3. Pipistrellus hesperus shows seasonal shifts in actual flight body temperature with a difference of 8–10°C between summer and winter. Spring and fall represent transition periods where the body temperature responds more directly to ambient temperature. Myotis californicus shows the same patterns only to a lesser extent. 4. 4. Low temperature flight appears to be an inherent physiological mechanism with no significant differences observed during laboratory experiments on a sexual or seasonal basis. 5. 5. Some variability is observed which appears to reflect the body condition and caloric and water balance. 6. 6. It is proposed that low temperature flight associated with winter activity is a mechanism adaptive for maintenance of water balance; but only incidentally of value as a feeding strategy.

An examination of the annual changes in brown fat deposits of Pipistrellus hesperus and Myotis californicus reveals: 1. 1. P. hesperus reaches peak brown fat levels in January and February, declining rapidly through March and April, then increases gradually through the remainder of the year. 2. 2. M. californicus , on the other hand, maintains peak levels of brown fat from December through February, decreasing gradually through August, then increasing rapidly in the fall. 3. 3.The major brown fat deposits for both species are interscapular, jugular, squamooccipitocervical and carotid bodies. 4. 4.The interscapular deposit (which accounts for 50–70% of all brown fat) appears to be a good index of brown fat dynamics. 5. 5.Brown fat appears to be important in maintaining body temperature during night at cold ambient temperatures.

Determination of age of several species of vespertilionid bats by counting incremental lines in dentine, cementum, and peridontal bone is described. The technique was most effective for aging Eptesicus fuscus and Lasionycteris noctivagans and less so for Myotis lucifugus. Incremental lines in specimens of Lasiurus cinereus and Lasiurus borealis were clearly defined, while those in a Myotis californicus were not. Longevity of E. fuscus and longevity and apparent age structure of M. lucifugus agree with the findings of published banding studies.

Crania and bacula of five taxa of small-footed bats of the leibii group, comprising two currently recognised species, Myotis californicus and M. leibii, were studied to elucidate their interrelationships. Canonical variate analysis of 14 cranial measurements shows the existence of three distinct nonoverlapping clusters corresponding to (i) M. californicus, (ii) M. I. ciliolabrum and M. I. melanorhinus, and (iii) M. I. leibii. The results of the morphometric analyses do not support the claim that M. I. leibii and M. I. melanorhinus intergrade in Oklahoma. The taxonomic interpretation of the results is that the western forms of M. leibii represent a separate species M. ciliolabrum (Mcrriam). The bacula of the taxa studied lack distinctive characters that would allow one to discriminate between the species of the leibii group.

An examination of warming rates of chest muscle in relation to rectal temperature and subsequent thermal mapping of selected tissues in active bats has shown the following trends: 1. 1. During arousal, chest muscle warms slightly faster than rectal temperature in Pipistrellus hesperus , Antrozous pallidus, Myotis californicus, M. thysanodes. Eptesicus fuscus , and Tadarida brasiliensis , whereas in Plecotus townsendii chest muscle warms twice as fast as rectal. 2. 2. Bats that warmed sufficiently to initiate flight in the laboratory had interscapular temperatures that were higher than rectal, brain, or adjacent flight muscles. 3. 3. Field data, however, indicate interscapular temperatures to be lower than flight muscle temperature, especially following periods of sustained flight. 4. 4. Both laboratory and field data show that certain bats are capable of coordinated and sustained flight at tissue temperatures well below recognized homeothermic levels.

Bats were netted at a desert spring in southern Nevada for a total of 70 nights covering each month of the year. Two species, Pipistrellus hesperus and Myotis californicus, were active throughout the year with peaks of seasonal activity during the warmer months. Antrozous pallidus was netted in all seasons of the year. Air temperature was a major factor affecting seasonal and nightly activity with more bats being netted at higher temperatures. However, both M. californicus and P. hesperus were active at air temperatures between −8° and 31 °C. During the warmer months, when air temperatures remained above 15°C for the entire night, both species sustained activity throughout much of the night, but in winter months, they were active only shortly after dusk and activity ceased when air temperatures dropped. Evidence for foraging and insect activity during the winter is presented. The hypothesis of continued year-round activity of bats in warmer areas of the southwest is presented as an alternative to hibernation or migration.

Various aspects of night roosting behavior were observed for four species of desert bats. Variability in night roost utilization was found for those species for which adequate observations were available. Myotis californicus roosted primarily in desert shrubs or trees, depending on availability. Pipistrellus hesperus utilized rock, rock crevices, and desert shrubs as primary roosting sites, rock being preferred when in close proximity to water. Antrozous pallidus was more flexible in roosting behavior, utilizing small trees, rock crevices, and an abandoned shed. In contrast, Tadarida brasiliensis roosted in a bridge expansionjoint where they were also found during daylight hours. Night roosting for digestion and subsequent weight loss reduces wing loading, thereby allowing considerable energy conservation in further foraging activity or long flights back to day roosts. During daylight hours, bats seek shelter in a wide variety of habitats. Day roosts have been described in numerous previous studies. Existing data on night roosts, however, are limited and have resulted mainly from accidental encounters in buildings, bridges, mines, caves, and rock crevices (Barbour and Davis 1969). In desert areas bat activity is concentrated near free water, which may be located at a considerable distance from roosting sites. There are, however, numerous isolated mountain ranges and adequate vegetation which could provide suitable night shelter. Where typical roosting sites occur adjacent to a water source, night roosts for some species of desert bats have been described (Dalquest 1953; Krutzsch 1954; Orr 1954; Cross 1965; Barbour and Davis 1969; Poche and Ruffner 1975). In this study we attempted to locate and describe night roosts in areas of the Mojave Desert where night roosts have not previously been identified. MATERIALS AND METHODS. Bats used for roosting behavior observations were collected at various locations in southern Nevada and northern Arizona (600-1480 m elevation) during the period July-September 1975. Roosting behavior observations were made on 34 Myotis californicus, 32 Pipistrellus hesperus, 26 Antrozous pallidus, and 24 Tadarida brasiliensis.

During the period between August 13 and 24, 1938, the writer collected fourteen Myotis californicus caurinus Miller and four Myotis evotis evotis (A. Allen) at Nelscott, Oregon, and a single Myotis californicus caurinus near McMinnville, Oregon. Nelscott is a seashore resort and the bats obtained there were taken from their daytime hiding places in the coniferous forest about one mile from the village. Small streams and a nearby freshwater lake might serve for the development of probable arthropod intermediate hosts of the trematodes found.

The 0. P. Silliman collection of mammals came to the Museum of Vertebrate Zoology as a gift from Mr. Robert L. Rudd. Most of the specimens were collected and prepared by J. C. von Bloeker and R. L. Rudd. Identifications on the labels are in the handwriting of von Bloeker. Recently, while arranging the collection for cataloging, I examined the specimens upon which the name Myotis ruddi Silliman and von Bloeker (Proc. Biol. Soc. Washington, 51: 167, 1938) was based. All these, except two already in the Museum of Vertebrate Zoology collection, were present in the Silliman collection and with the name Myotis ruddi on the labels. I found that these specimens actually included four species, and that Myotis ruddi is a synonym of Myotis volans longicrus (True). Errors in the technique of labelling and preparing skulls and in identification were evident. All specimens assigned to ruddi were melanistic or nearly so. Six, including the type, are M. volans longicrus, one is Myotis yumanensis saturatus, two are skins of Myotis lucifugus alascensis of which one is accompanied by a skull of Myotis yumanensis and the other by a skull of Myotis californicus. The specimens originally in the Silliman collection were from Monterey County, California. The describers also included one in the collection of the Museum of Vertebrate Zoology from San Benito County, California. Taking the specimens in the order listed in the original description the specimen numbers are now as follows: Lake Espinosa, 50 feet elevation, Salinas Valley, Monterey County: orig. no. 6895, J. C. von Bloeker; 87, 0. P. Silliman; 107900, Mus. Vert. Zool. This specimen is represented by the skin of an immature Myotis lucifugus alascensis. It agrees with other skins of this species from the same locality except that it is slightly darker than the darkest (also an immature) of the other specimens. This series of sixteen specimens exhibits a considerable amount of variation in color. The paler specimens had been labeled Myotis yumanensis sociabilis and the darker ones, except for the one referred to ruddi, correctly assigned to Myotis lucifugus alascensis. The skull accompanying this skin represents an adult Myotis californicus. Fading of the writing on the original skull label may have been the cause for the error since the original label shows that the original number had been retraced, mistakenly, after the skull and label had gone through the cleaning process. It is also evident that some error had been made in recording measurement data on the skin label for some of the measurements had been written over and now are larger than those recorded in the field catalogue of the collector. Chews Ridge, 5000 feet elevation, Santa Lucia Mountains, Monterey County: orig. no. 6457, J. C. von Bloeker; 88, 0. P. Silliman; 107893, Mus. Vert. Zool. This specimen includes a skin of an immature Myotis lucifugus alascensis which had been badly damaged when the bat was shot. The skull associated with the skin is that of an adult Myotis yumanensis. Complete evidence that it is not to be correctly associated with the skin is that the skull is perfect and undamaged 48 Vol.30, No. 1

Bats were captured in a mist net at White Spot Spring, Desert Game Range, Clark County, Nevada during the months September through May for a total of 21 mist net nights. Time of capture, air temperature, and wind conditions are given for each species. Two species, Pipistrellus hesperus and Myotis californicus were active throughout the fall and winter. Pipistrellus was netted at air tempera- tures ranging from 10 to 310 C. Myotis californicus was netted at air temperatures of 20 to 270 C. Approximately 48% of the Myotis were taken at air temperatures be- tween 2o and 60 C. and approximately 11% of the Pipistrellus were netted at air temperatures of 50 C. or below. A third species Antrozous pallidus was netted in low numbers at air temperatures as low as 20 C. Studies of bat activity have usually been conducted during the spring, summer, and early fall months when bat activity is highest. Since bat activity is low or non-existent in temperate areas during the fall and winter, few data on activity are available for these seasons. The present study provides some indications of fall and winter activity for certain species found to be active at these seasons in southern Nevada. DESCRIPTION OF THE STUDY AREA. White Spot Spring is lo- cated at 4460 feet elevation, on the north-facing slope of the Las Vegas Range, Desert Game Range, Clark County, Nevada. The spring flow is contained within a stone tank which is approximately 11.5 feet square by 2 feet deep. The tank was usually full of water. It is bordered on one side by Tamarix spp. and Phragmites communis. The surrounding area consisting or rolling hills is covered by various desert shrubs in- cluding Coleogyne ramosissima, Larrea divaricata, Yucca schidigera, and Atriplex canescens.