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Results for “Acta Chiropterologica”

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At least 19 recordsLinked to original sources

USGS2002

Feeding habits of the endangered Ozark big-eared bat (Corynorhinus townsendii ingens) relative to prey abundance

Feeding habits of the endangered Ozark big-cared bat (Corynorhinus townsendii ingens) in eastern Oklahoma, USA, were studied from July 1987 through July 1988. Diets were determined from microscopic analysis of fecal pellets and compared with arthropods collected in Malaise traps. Although lepidopterans comprised only 21.5% of the available prey, they occurred in > 90% of the pellets examined and accounted for > 85% of the volume of prey consumed. Dipterans, coleopterans, and homopterans occurred in 18.3%, 10,6%, and 6.7% of the feces, respectively, but each accounted for < 5% of the volume of prey consumed. Trichopterans, hymenopterans, and neuropterans also were found in feces but in trace amounts. Our results support the classification of C. t. ingens as a moth specialist, but additional insights are needed to fully understand how its feeding tactics conform to the allotonic frequency hypothesis (i.e., avoiding detection by cared moths). Conservation of this highly endangered North American bat will require, in part, maintenance of habitats capable of supporting abundant populations of Lepidoptera.

Acta Chiropterologica↗

USGS2003

Internal cave gating for protection of colonies of the endangered gray bat (Myotis grisescens)

Persistent human disturbance is a major cause for the decline in populations of many cave-dwelling bats and other sensitive cave-obligate organisms. Cave gating has been used to eliminate human disturbance, but few studies have assessed directly the impact of such management activities on resident bats. In northeastern Oklahoma, USA, 25 entrances of caves inhabited by two endangered species and one endangered subspecies of bats are protected from human entry with internal gates. Because cave gates may impede ingress and egress of bats at caves, we evaluated the impacts of internal gates before and after their construction at six colonies of endangered gray bats ( Myotis grisescens ) from 1981 to 2001. No caves were abandoned by gray bats after the construction of internal gates; in fact, total numbers of gray bats using the six caves increased from 60,130 in 1981 to 70,640 in 2001. Two caves harbored more gray bats after gating, and three caves had no change in gray bat numbers after gating. We also compared initiations of emergences at three gated and three open-passage caves in June and July 1999–2000. No differences in timing of initiation of emergence were found between colonies in gated versus open-passage caves. Our results support the use of internal gates to protect and thereby enhance recovery of colonies of endangered gray bats. Additional research is encouraged to confirm that our observations on gray bats are generally applicable to other species of cave-dwelling bats.

Oklahoma↗

USGS2008

Evaluation of morphological indices and total body electrical conductivity to assess body composition in big brown bats

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 r2 = 0.82, P < 0.001) followed by TOBEC measurement (partial r2 = 0.08, P < 0.001) and to a minor extent head length (partial r2 = 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. ?? Museum and Institute of Zoology PAS.

Acta Chiropterologica↗

USGS2009

Habitat occupancy and detection of the pacific sheath-tailed bat (emballonura semicaudata) on aguiguan, commonwealth of the northern Mariana Islands

Occupancy analysis was used to quantify Pacific sheath-tailed bat (Emballonura semicaudata) foraging activity and its relationship to forest structure and proximity to cave roosts on Aguiguan Island in the Commonwealth of the Northern Mariana Islands. Bat occurrence was most closely associated with canopy cover, vegetation stature and distance to known roosts. The metrics generated by this study can serve as a quantitative baseline for future assessments of the status of this endangered species following changes in habitat due to management activities (e.g., feral goat control) or other factors (e.g., typhoon impacts). Additionally, we provide quantitative descriptions of the echolocation calls of E. semicaudata. Search-phase calls were characterized by a relatively narrow bandwidth and short pulse duration typical of insectivores that forage within vegetative clutter. Two distinctly characteristic frequencies were recorded: 30.97 ?? 1.08 kHz and 63.15 ?? 2.20 kHz ?? Museum and Institute of Zoology PAS.

Acta Chiropterologica↗

USGS2009

Does variation in cranial morphology of Myotis occultus (Chiroptera: Vespertilionidae) reflect a greater reliance on certain prey types?

Few studies have investigated the relationship between morphological variation and local feeding habits of bats in the United States. We used discriminant function analysis (DFA) to compare cranial morphology of Myotis occultus from southern Colorado, and central, and southern New Mexico. We analyzed guano collected from maternity colonies in southern Colorado and central New Mexico to compare food habits. Bats from southern Colorado had the smallest values on the first canonical variate (CV1) that also reflected the smallest measurements of key cranial and dental variables, including height of coronoid process, width of molar, and dentary thickness. Bats from central and southern New Mexico had intermediate and large CV1 values, respectively. Overall, CV1 discriminated individuals occurring in southern Colorado and central New Mexico from those in southern New Mexico. CV2 served best at discriminating bats of southern Colorado from those of central New Mexico. Comparison of food habits revealed that individuals from southern Colorado ate more soft-bodied prey items (e.g., flies) whereas bats from central New Mexico ate more hard-bodied prey items (e.g., beetles). As shown in earlier studies that investigated relationships between morphology and diet of insectivorous bats, we found differences in skull morphology of M. occultus that were correlated with differences in food habits.

Acta Chiropterologica↗

USGS2011

Status and Natural History of Emballonura Semicaudata Rotensis on Aguiguan, Mariana Islands

Pacific sheath-tailed bats ( Emballonura semicaudata rotensis ) in the Mariana Islands declined greatly in abundance and distribution during the 20th century. The small island of Aguiguan now supports the only persisting population. We studied abundance and natural history of this population from 1995–2008. There was a likely population increase during the study, with 359–466 (minimum and maximum) bats counted at caves in 2008. Bats roosted only in caves, primarily those of relatively larger size. Bats were detected in only seven of 95 caves; three caves were always occupied when surveyed. One cave consistently had the largest colony ( ± SD = 333 ± 33.6 in 2008). Others held 1–64 bats. Cave environments showed no complexities in temperature or humidity. Preliminary observations indicate a litter size of one and the possibility of birthing timed to coincide with the transitional period leading into the rainy season (June–July). We review potential threats to E. s. rotensis on Aguiguan and make suggestions for conservation.

Acta Chiropterologica↗

USGS2011

Nocturnal activity patterns of northern myotis (Myotis septentrionalis) during the maternity season in West Virginia (USA)

Nocturnal activity patterns of northern myotis (Myotis septentrionalis) at diurnal roost trees remain largely uninvestigated. For example, the influence of reproductive status, weather, and roost tree and surrounding habitat characteristics on timing of emergence, intra-night activity, and entrance at their roost trees is poorly known. We examined nocturnal activity patterns of northern myotis maternity colonies during pregnancy and lactation at diurnal roost trees situated in areas that were and were not subjected to recent prescribed fires at the Fernow Experimental Forest, West Virginia from 2007 to 2009. According to exit counts and acoustic data, northern myotis colony sizes were similar between reproductive periods and roost tree settings. However, intra-night activity patterns differed slightly between reproductive periods and roost trees in burned and non-burned areas. Weather variables poorly explained variation in activity patterns during pregnancy, but precipitation and temperature were negatively associated with activity patterns during lactation. ?? Museum and Institute of Zoology PAS.

Acta Chiropterologica↗

USGS2014

Effects of cave gating on population trends at individual hibernacula of the Indiana bat ( Myotis sodalist )

Installing gates at cave entrances to protect hibernating bat colonies is a widespread conservation action, particularly for endangered bat species such as the Indiana bat ( Myotis sodalis ). However, there is surprisingly little evidence on the efficacy of gates for improving population growth rates. We used change-point models to determine the effects of gate construction on Indiana bats. We estimated population growth rates at 20 hibernacula pre- and post-gating and quantified the change in population growth rates after gate installation. Hibernacula with increasing growth rates prior to gate placement all experienced decreased growth rates after installation. For hibernacula with declining growth rates prior to construction, growth rates increased moderately after installation. When weighted by population size, average change in growth rates across all 20 hibernacula was negative. Our results suggest that use of gates at hibernacula with growing populations may relate to unintended declines in growth rates but that, at hibernacula with declining populations, installation of gates may lead to moderate increases in local population growth rates.

Acta Chiropterologica↗

USGS2014

Estimating sample size for landscape-scale mark-recapture studies of North American migratory tree bats

Concern for migratory tree-roosting bats in North America has grown because of possible population declines from wind energy development. This concern has driven interest in estimating population-level changes. Mark-recapture methodology is one possible analytical framework for assessing bat population changes, but sample size requirements to produce reliable estimates have not been estimated. To illustrate the sample sizes necessary for a mark-recapture-based monitoring program we conducted power analyses using a statistical model that allows reencounters of live and dead marked individuals. We ran 1,000 simulations for each of five broad sample size categories in a Burnham joint model, and then compared the proportion of simulations in which 95% confidence intervals overlapped between and among years for a 4-year study. Additionally, we conducted sensitivity analyses of sample size to various capture probabilities and recovery probabilities. More than 50,000 individuals per year would need to be captured and released to accurately determine 10% and 15% declines in annual survival. To detect more dramatic declines of 33% or 50% survival over four years, then sample sizes of 25,000 or 10,000 per year, respectively, would be sufficient. Sensitivity analyses reveal that increasing recovery of dead marked individuals may be more valuable than increasing capture probability of marked individuals. Because of the extraordinary effort that would be required, we advise caution should such a mark-recapture effort be initiated because of the difficulty in attaining reliable estimates. We make recommendations for what techniques show the most promise for mark-recapture studies of bats because some techniques violate the assumptions of mark-recapture methodology when used to mark bats.

Acta Chiropterologica↗

USGS2015

Roost selection by Rafinesque’s big-eared bats ( Corynorhinus rafinesquii ) in a pristine habitat at three spatial scales

Although several studies have described roost use by Rafinesque's big-eared bats ( Corynorhinus rafinesquii ), few studies have examined roost selection. We examined roost use and selection by Rafinesque's big-eared bat at the tree, stand, and landscape scales during the maternity season in pristine old-growth habitat in the Coastal Plain of South Carolina. We located 43 roosts (14 maternity, 29 solitary) through cavity searches and radio-telemetry. Maternity colonies and solitary individuals selected roosts based on similar characteristics. The best model explaining roost selection by all bats included tree and stand characteristics; landscape factors had little influence on roost use. Bats selected large diameter trees in areas with a high density of trees with cavities in the surrounding area. Most roosts (67.4%) were in water tupelo ( Nyssa aquatica ) in semi-permanently flooded and saturated areas. Half of maternity roost cavities had upper bole openings whereas only 25.8% of solitary roosts had upper bole openings. Bats that roosted with maternity groups stayed in roosts for significantly shorter periods of time (1.3 ± 0.1 days) and used significantly more roost trees (5.0 ± 0.6 roosts) than adult males (3.8 ± 1.10 days, 2.3 ± 0.4 roosts, respectively). Maternity colony use of cavities with upper bole openings and shorter residency times suggest that predator avoidance may have been an important factor governing roosting behavior of maternity colonies in this area. Our results suggest that retention of large diameter, hollow trees in wetland areas will benefit Rafinesque's big-eared bat individuals and maternity colonies in this area.

South Carolina↗

USGS2015

Not to put too fine a point on it - does increasing precision of geographic referencing improve species distribution models for a wide-ranging migratory bat?

Bat specimens held in natural history museum collections can provide insights into the distribution of species. However, there are several important sources of spatial error associated with natural history specimens that may influence the analysis and mapping of bat species distributions. We analyzed the importance of geographic referencing and error correction in species distribution modeling (SDM) using occurrence records of hoary bats ( Lasiurus cinereus ). This species is known to migrate long distances and is a species of increasing concern due to fatalities documented at wind energy facilities in North America. We used 3,215 museum occurrence records collected from 1950–2000 for hoary bats in North America. We compared SDM performance using five approaches: generalized linear models, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy models. We evaluated results using three SDM performance metrics (AUC, sensitivity, and specificity) and two data sets: one comprised of the original occurrence data, and a second data set consisting of these same records after the locations were adjusted to correct for identifiable spatial errors. The increase in precision improved the mean estimated spatial error associated with hoary bat records from 5.11 km to 1.58 km, and this reduction in error resulted in a slight increase in all three SDM performance metrics. These results provide insights into the importance of geographic referencing and the value of correcting spatial errors in modeling the distribution of a wide-ranging bat species. We conclude that the considerable time and effort invested in carefully increasing the precision of the occurrence locations in this data set was not worth the marginal gains in improved SDM performance, and it seems likely that gains would be similar for other bat species that range across large areas of the continent, migrate, and are habitat generalists.

Acta Chiropterologica↗

USGS2015

Ultraviolet vision may be widespread in bats

Insectivorous bats are well known for their abilities to find and pursue flying insect prey at close range using echolocation, but they also rely heavily on vision. For example, at night bats use vision to orient across landscapes, avoid large obstacles, and locate roosts. Although lacking sharp visual acuity, the eyes of bats evolved to function at very low levels of illumination. Recent evidence based on genetics, immunohistochemistry, and laboratory behavioral trials indicated that many bats can see ultraviolet light (UV), at least at illumination levels similar to or brighter than those before twilight. Despite this growing evidence for potentially widespread UV vision in bats, the prevalence of UV vision among bats remains unknown and has not been studied outside of the laboratory. We used a Y-maze to test whether wild-caught bats could see reflected UV light and whether such UV vision functions at the dim lighting conditions typically experienced by night-flying bats. Seven insectivorous species of bats, representing five genera and three families, showed a statistically significant ‘escape-toward-the-light’ behavior when placed in the Y-maze. Our results provide compelling evidence of widespread dim-light UV vision in bats.

Arizona, Colorado↗

USGS2020

Temporal and spatial changes in Myotis lucifugus acoustic activity before and after white-nose syndrome on Fort Drum Army Installation, New York, USA

Changes to bat distribution and habitat associations at the local to sub-landscape scale in the post white-nose syndrome (WNS) environment have received little attention to date despite being critical information for managers. To better understand the spatial nature of bat population declines, we modelled both activity patterns and occupancy from acoustic surveys for the Myotis lucifugus (little brown bat) on Fort Drum Military Installation in New York, USA over 15 summers (2003–2017) that span the pre-WNS, WNS-advent (2008) and post-WNS periods, using a set of generalized linear mixed models and geospatial analysis. Our best supported model indicated significant differences between years with significant declines in activity post-WNS. M. lucifugus activity was most closely associated with woody wetland habitats over the study period, however, the spatial patterns of high activity areas were variable over years, with the areal extent of these high activity areas decreasing post-WNS. Our best supported occupancy model varied by year. However, the null occupancy model [Ψ(.)] was either competing (within 2 ΔAIC units) or was the best supported model. Meaning that none of our environmental variables seemed to impact occupancy, and when they did, these differences were not significant. There was high disagreement between our relative activity models and predictions compared to our occupancy models, suggesting that geographic spatial scale and the resolution of the data impacts model outcome. Our results indicate that continued acoustic monitoring of bat species in the Northeast to assess ongoing temporal and spatial changes in habitat associations and to provide direction for future mist-netting studies should rely more on relative activity as the metric of choice rather than site occupancy.

New York↗

USGS2021

Forecasting the distribution of a range-expanding bat reveals future response to climate change and habitat

Many terrestrial vertebrate species are exhibiting geographic distribution changes including poleward range limit shifts in response to increases in regional temperature. Bats are a highly mobile taxa capable of rapid responses to changes in abiotic or biotic conditions. In North America, recent extralimital records of the non-hibernating Lasiurus seminolus (Seminole bat) have been attributed to climate change, however such attributions remain speculative and potentially subject to sampling bias in the form of increased recent sampling efforts at latitudes north of the historical range. We used historical occurrence records and simple environmental variables within a Maxent modeling framework to model the historical distribution of suitable areas for this species. We transferred the model using near current environmental conditions and measured the ability of the model to capture the apparent expansion in distribution using recent extralimital occurrence records. This measure indicated a distribution expansion, largely attributed to increasing minimum temperatures. We used the model to forecast the expansion in distribution of suitable areas at three 20-year intervals and various climate change scenarios and provide extrapolation risk maps for each scenario. Although increasing temperatures may increase potentially occupiable areas, the species is associated with forests and often roosts in Pinus spp. (pines). This suitable habitat is reduced in presence to the northwest of the species’ range, which may constrain the future species expansion despite favorable temperatures. We demonstrated this effect by mapping limiting factors through future climate change scenarios. We discovered a broad shift of effects that constrained the distribution from minimum temperature to a metric of evergreen cover type as time and climate intensity increased. Although uncertainties exist, we predict further expansion of the Seminole bat widely over the next 60 years across the eastern United States where suitable habitat and climate conditions converge. Our results appear consistent with other bat species showing similar range extensions and in turn provide further evidence that bats may serve as bioindicators of global change.

Alabama, Arkansas, Florida, Georgia, Illinois, Ind↗

USGS2022

Seasonal activity patterns of bats in high-elevation conifer sky islands

In the southern Appalachian Mountains of the southeastern USA, bat communities in high-elevation habitats tend to be relatively under-surveyed. High-elevation habitats may provide important habitat to certain species (i.e., migratory tree bats), and may serve as climate refugia during droughts or high temperatures. We conducted an opportunistic acoustic survey of bat communities in ten survey areas in high elevation (1,585–1,920 m a.s.l.) montane Picea rubens (red spruce)- Abies fraseri (Fraser fir) forest in the southern Appalachian Mountains of western North Carolina. In each survey area, we randomly placed three full spectrum acoustic detectors ( N = 30) during three seasons (spring, summer and fall) in 2015. We deployed each detector for two five-day periods during each season ( n = 900 survey nights). Although we detected seven bat species/groups during the surveys, 73% of echolocation files were attributed to Lasiurus cinereus (hoary bat) and Lasionycteris noctivagans (silver-haired bat). Generally rare in the Appalachians and typically present only at low densities in the summer at mid- and low-elevations, both species were detected at all sites during all seasons. Overall, mean nightly activity of bats was higher in the summer than the spring or fall. We observed 3.7–5 times greater activity of L. cinereus in spruce-fir forests during the summer compared to spring and fall, whereas L. noctivagans had 1.3–5 times more activity in the summer compared to other seasons. After accounting for precipitation events, our finite mixture models showed that season, temperature, elevation, and canopy height influenced L. cinereus activity, whereas season and temperature affected L. noctivagans activity. Our observations suggest that high-elevation spruce-fir forests are providing summer foraging and possibly day-roosting habitat of tree bats not previously documented this far south in North America.

North Carolina↗

USGS2026

Day-roost use by ‘ōpe‘ape‘a, the Hawaiian hoary bat (Lasiurus semotus)

The ‘ōpe‘ape‘a, also known as the Hawaiian hoary bat ( Lasiurus semotus ; family Vespertilionidae), is a solitary, insectivorous, foliage-roosting endemic species. Over a three-year period, we investigated day-roost lability and fidelity of 35 bats at 52 roosts (for a total of 544 days of observation), and roost emergence and return patterns of 46 bats at 50 roosts (for a total of 277 days of observation). ‘Ōpe‘ape‘a exhibited low roost lability, typically using few roosts and switching roosts infrequently. Juveniles and reproductive females exhibited particularly low lability, whereas non-reproductive adults, especially males, displayed higher lability. Roost fidelity was generally high, with most bats consistently returning to the same roost or set of roosts. We also evaluated long-term use of roosts at 20 trees from 2019 to 2022. Six roost trees were used over a span of at least 180 days, and of these, three were used by multiple individuals that included maternity groups. We documented a maternity ‘cluster’ composed of multiple neighboring roosts used by different mother-pup groups and solitary bats during the same reproductive season. Measures of day-roost emergence times, nocturnal period spent at roosts, and number of nighttime departures showed high variability, were not significantly different among sex or reproductive groups and exhibited no seasonal trends. The study demonstrated that ‘ōpe‘ape‘a generally remain at the same day-roost for extended periods, unlike other tree-dwelling species, particularly lasiurines. The findings also suggest that individuals may prioritize familiar roosts and home range resources over exploring new roosts, potentially due to the permanence of suitable foliage roosts and predator avoidance strategies.

Hawaii↗

USGS2007

A comparison of conventional capture versus PIT reader techniques for estimating survival and capture probabilities of big brown bats (Eptesicus fuscus)

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 (P?? = 0.93-1.00) than when derived from conventional techniques (P?? = 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. ?? Museum and Institute of Zoology PAS.

Acta Chiropterologica↗

USGS2001

Roosting habits of four bat species in the Black Hills of South Dakota

The availability of suitable roosts influences the distribution and abundance of bats. Quantifying roosting requirements is a necessary step toward effectively monitoring, managing, and conserving bats. Our objectives were to locate and characterize the natural, daytime summer roosts of Myotis septentrionalis , M. thysanodes , M. volans , and Eptesicus fuscus in the Black Hills of South Dakota, USA and compare local roosts to those used in other regions. Bats were marked with radio transmitters and followed to roosts. We successfully tracked 37 bats of four species to a total of 81 roosts. Myotis septentrionalis and E. fuscus consistently used trees, while M. thysanodes and M. volans used both trees and rock crevices. Roost trees were consistently among the largest available and were found in areas of relatively high snag densities. Maintaining forests with high snag densities and large trees will likely benefit bat populations in the Black Hills. All species switched roosts, but generally remained within small (≈4 km 2 ) areas. Lactating M. thysanodes changed roosts together while carrying young. Fidelity to roosts and roost areas was demonstrated by bats in the Black Hills.

Acta Chiropterologica↗