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Emerging pathogens can cause mass mortalities in susceptible species. High host mortality, in turn, can alter species composition, community structure and function. White-nose syndrome (WNS) is an emerging wildlife disease introduced to North America that has decimated millions of cave-dependent bats. For areas affected by WNS, there have been reports of community compositional changes, but compensatory changes to species composition following WNS has only been suggested, not reported. To determine if compensatory changes to species composition occur following WNS, we used seven years of data from statewide citizen science mobile bat acoustic routes initiated by the Ohio Division of Wildlife in 2011. We hypothesized that migratory bat abundance increased and cave-dependent bat abundance decreased following the emergence of WNS in the study period (2011–2017). Our hypothesis was based on the higher susceptibility of cave-dependent bats than migratory bats to infection and WNS mortality. We used two sets of models to identify abundance trends of each species found in Ohio and species grouped by wintering and roosting behaviors that are putatively important to changes in species composition post-WNS. Following WNS, we found a compensatory change in species in summer months from cave-dependent, cavity-roosting species (Myotis species and Eptesicus fuscus) to migratory, cavity-roosting species (Nycticeius humeralis and Lasionycteris noctivagans). However, for species that roost in foliage in the summer, we did not detect an increase in migratory species (Lasiurus borealis and Lasiurus cinereus) paired with a decrease in cave-dependent species (Perimyotis subflavus). The observed post-WNS trends in bat populations could suggest shifts in bat species composition in other areas where WNS is established.

It generally is accepted that bats emit ultrasonic vocalizations that function for echolocation purposes as well as for communication. We tested whether male or female big brown bats (Eptesicus fuscus) responded to variation in echolocation calls of the opposite sex in a manner that would suggest calls are used in a mating context. We presented 31 female and 10 male big brown bats with ultrasonic playbacks of differentially mating (i.e., high frequency copulators = HM versus low-frequency copulators = LM) individuals of the opposite sex. We measured 1) which side of the arena each subject selected first (HM versus LM), and 2) duration spent (seconds) on each side of the arena (HM versus LM). For both of these measures (i.e., first choice and duration) male subjects were more likely to select the echolocation calls of HM females, but the same respective tests determined that female subjects did not select echolocation calls of frequently copulating males over calls of infrequently copulating males. These r...

There are numerous records of conjoined twinning in humans and domesticated animals, but many fewer for wild animals because of the early death of conjoined twins. We here describe the incidental discovery and skeletal anatomy of a wild-caught bat fetus with two heads. To our knowledge, this is only the second conjoined bat fetus described, and the first conjoined Artibeus phaeotis. We also revisit the anatomy of the first conjoined bat that was described, a stillborn Eptesicus fuscus.

The use of different roost types by Daubenton's bats (Myotis daubentonii) during reproduction was investigated in two adjacent river valleys in northeastern Scotland. Forty-six individuals from six colonies were radiotracked during the summers of 2004–2006. The frequency of roost switching varied with reproductive status, and was lowest in lactating females and highest in non-reproductive females, which changed roosts on average once every 5.0 and 1.5 days, respectively. Although Daubenton's bats regularly switched roosts, strong faithfulness to the roosting area was apparent regardless of whether they formed maternity colonies in trees or buildings. Although most roosts found at both study areas were in trees, lactating females and juveniles in one valley roosted only in trees whereas in the other they roosted exclusively in buildings, in which ambient temperatures were significantly higher. The implications of roosting habits for the transmission of European bat lyssavirus are discussed.

Although several studies have reported inter- and intra-individual variation in the echolocation pulses of big brown bats, relatively few have explored its function in the context of courtship and mating. In this study, we tested for sex and seasonal differences in the echolocation pulses of male and female big brown bats, and related these differences to mating activity. We recorded the echolocation pulses of adult female and male big brown bats in a controlled laboratory environment during the mating and three non-mating seasons. Factor analysis was used to reduce the number of call variables into two principle components (PC1 and PC2). Call components related to PC2 were significantly sexually dimorphic in the mating season. However, no call components were significantly sexually dimorphic in the non-mating season. In addition, we found a significant correlation between PC1 and the mating score of male bats. There was no significant correlation between principle components and the mating score of femal...

As technology has evolved, bat researchers have relied more heavily on using acoustic techniques to collect data on bat communities. Acoustic data can be collected actively, where the researcher is present at the sampling point and follows the bat with the detector, or passively, where the researcher is not present and the detector is set out by itself. Active sampling can yield longer, clearer calls, and is only conducted during part of the night (usually from sunset to about 02:00 hours) for short bouts (20 minutes). By contrast, passive sampling can yield lower quality calls, but procedures are easily repeatable and data can be used to measure temporal variation in activity throughout the night and detect individuals and species that are missed during active sampling. Researchers are increasingly attempting to monitor and compare bat communities over time, including sites where both active and passive sampling have occurred. However, these two techniques can yield different detection probabilities and the extent to which data collected using these two techniques can be compared is unclear. Thus, in July 2017 we simultaneously collected acoustic data actively and passively to compare detection probabilities of bats at the Savannah River Site, South Carolina, USA. Using Anabat Express detectors, we detected five species or species groups (Eptesicus fuscus/Lasiurus cinereus, L. borealis/L. seminolus, Perimyotis subflavus, Myotis austroriparius, and Nycticeius humeralis) using each method. Using single season occupancy modeling, we found that method (passive vs. active sampling) had a significant effect on detection probabilities of all species, and that passively sampling throughout the night yielded the highest detection probability for all species. As a result, if differences in detection probability are not taken into account, comparison of historical active datasets with current passive datasets could lead to different insights into habitat use by similar bat communities. Based on our findings, we recommend that researchers use passive sampling throughout the night when studying and monitoring bat communities.

The Chiroptera do not have an extensive fossil record. To date, for the Quaternary of Brazil, only material from Minas Gerais, Sao Paulo, Bahia and Goias States are known. For Rio Grande do Sul State, in contrast to the studies about the Pleistocene megafauna, little is known about Holocene small mammals, this being the first contribution about the Chiroptera of this age found in Rio Grande do Sul. The material was excavated from two archaeological sites, dating from ± 9,400 yrs BP to ± 4,250 yrs BP. The taxa recorded were: Chrotopterus auritus, Pygoderma bilabiatum (Phyllostomidae); Eptesicus brasiliensis, E. fuscus, Myotis cf. Myotis ruber, Vespertilionidae aff. Lasiurus (Vespertilionidae); Tadarida brasiliensis, and Molossus molossus (Molossidae). The presence of E. fuscus extends its Holocene distribution far southwards into the south temperate zone; its previous Quaternary occurrences were in Bahia State, Brazil, as well as in Venezuela, Mexico and the USA.

Bat researchers have used both morphological indices and total body electric conductivity (TOBEC) as proxies for body condition in a variety of studies, but have typically not validated these indices against direct measurement of body composition. We quantified body composition (total carcass lipids) to determine if morphological indices were useful predictors of body condition in big brown bats (Eptesicus fuscus). We also evaluated body composition indirectly by TOBEC using EM-SCAN® technology. The most important predictors of body composition in multiple regression analysis were body mass-to-forearm ratio (partial r 2 = 0.82, P < 0.001) followed by TOBEC measurement (partial r 2 = 0.08, P < 0.001) and to a minor extent head length (partial r 2 = 0.02, P < 0.05). Morphological condition indices alone may be adequate for some studies because of lower cost and effort. Marking bats with passive integrated transponder (PIT) tags affected TOBEC measurements.

We compared conventional capture (primarily mist nets and harp traps) and passive integrated transponder (PIT) tagging techniques for estimating capture and survival probabilities of big brown bats (Eptesicus fuscus) roosting in buildings in Fort Collins, Colorado. A total of 987 female adult and juvenile bats were captured and marked by subdermal injection of PIT tags during the summers of 2001–2005 at five maternity colonies in buildings. Openings to roosts were equipped with PIT hoop-style readers, and exit and entry of bats were passively monitored on a daily basis throughout the summers of 2002–2005. PIT readers ‘recaptured’ adult and juvenile females more often than conventional capture events at each roost. Estimates of annual capture probabilities for all five colonies were on average twice as high when estimated from PIT reader data ( = 0.93–1.00) than when derived from conventional techniques ( = 0.26–0.66), and as a consequence annual survival estimates were more precisely estimated when using PIT reader encounters. Short-term, daily capture estimates were also higher using PIT readers than conventional captures. We discuss the advantages and limitations of using PIT tags and passive encounters with hoop readers vs. conventional capture techniques for estimating these vital parameters in big brown bats.

To maximise foraging efficiency, it is reasonable to expect animals to forage in the highest quality patches. Insectivorous bats should therefore travel to and forage at sites with the highest insect abundance. Since insects are ectothermic, their levels of activity should be higher in warmer areas, making these high quality patches for bats. A nightly temperature inversion occurring in the Cypress Hills (Saskatchewan, Canada) presented an opportunity to test our hypothesis that big brown bats (Eptesicus fuscus) select foraging sites based on temperature as a proxy for insect abundance. If temperature is an important determinant of the foraging behaviour of E. fuscus, we expect bats to forage in the warmest site closest to local night roosts. We tracked 18 bats for a total of 111 nights over two years and found that individuals often spent at least some of each foraging bout in an area where the temperature inversion was small or non-existent. Bats sometimes travelled up to 11 km to reach this site. Foraging in areas where the temperature inversion was small provides indirect evidence that local temperature fluctuations are not a major influence on the selection of foraging area by E. fuscus. Also, since there was little difference in the temperature between the nearby predicted foraging sites and actual foraging sites, we argue that the effect of temperature on insect activity cannot be used to predict foraging habitat selection by these bats. We found that the insect community of the foraging area was different than that of the roosting area, and that beetles were more abundant in the foraging site. Our data suggests that insect community composition is potentially a stronger direct influence on bat foraging behaviour than is temperature.

Insectivorous bats in their first year of life generally deposit less fat prior to hibernation than older bats of the same species. In the present study we explored the energy expenditures of first-year (sub-adult) and older than one year (adult) Daubenton's bats (Myotis daubentonii) during torpor and their patterns of roost site selection and fat accumulation in an artificial roost site, removing from the equation the effects of differences in aerial foraging behaviour by feeding them on non-aerial prey (mealworms). Sub-adult bats had oxygen consumption during torpor that averaged 2.75 × greater than adult individuals. In an artificial enclosure in which bats could fly freely and choose whether to roost inside or outside of a hollow brick, sub-adults gained body mass at a significantly lower rate (67.8 mg × day−1) than adults (100.3 mg × day−1), despite being fed non-aerial prey (mealworms). The difference in rates of mass accumulation (32.5 mg per day) far exceeded the theoretical influence of ...

The purpose of this study was to determine whether canine wear influences the diet of big brown bats (Eptesicus fuscus). We hypothesized that tooth wear reduces the ability to consume hard-bodied insects, such as beetles, and that older E. fuscus (those with worn canines) would thus include fewer beetles in their diet than younger individuals (those with less-worn canines) do. We examined 600 fecal pellets collected from 60 female bats captured at a single maternity colony in southeastern Alberta, Canada. The diets of two groups were similar in composition, despite considerable differences in canine wear. Diets were dominated by beetles (Coleoptera), which accounted for 30 to 40% of the identifiable food items. Younger bats included more beetles in their diet, although the difference was not statistically significant. The results suggest that older bats are still able to use their worn canines to effectively puncture hard exoskeleton, perhaps because of the angular shape of the worn teeth.

Roost availability may limit some bat populations, implying that there may be a selective advantage associated with the ability to reuse sites on an annual basis. We monitored aspen tree use by Eptesicus fuscus during multi-year studies (spanning up to 10 years) at the same site in Saskatchewan, Canada. We found that reuse of live trees over the medium-term (three years) was common and that, in some instances, reuse over the long-term (nine and 10 years) can occur. Our data also suggest that, over the medium-term, aspen roosts are reused by groups of bats more often than by solitary individuals. Our findings support the hypothesis that cavity roosting bats exhibit between year loyalty, not just to patches of forest but also to specific trees.