Maternity Colonies Research Articles

Relatedness within and among northern long-eared bat (Myotis septentrionalis) colonies at a local scale

We assessed parentage within and among maternity colonies of northern long-eared bats (Myotis septentrionalis (Trouessart, 1897)) in north-central Kentucky, USA, from 2011 to 2013 to examine colony social structure, formation, and membership dynamics. We intensively sampled colonies in close and remote (>10 km) proximity before and after targeted day-roost removal. Colonies were not necessarily composed of closely related individuals, although natal philopatry was common. Adjacent colonies often contained maternally related individuals, indicating that some pups did disperse, albeit not far from their natal home range. Whereas some young had been sired by males also collected on site, most had not, as would be expected since the species mates in fall near hibernacula across a wider landscape. The number of parentages that we inferred among colonies, however, suggests that outside the maternity season, social groups may be relatively flexible and open. Analysis of microsatellite DNA data showed a low FST(0.011) and best fit to a model of one multilocus genotypic cluster across the study area. We observed high turnover in colony membership between years in all colonies, regardless of roost-removal treatment. Our results suggest that female northern long-eared bats exhibit fidelity to a general geographic area and complex, dynamic social–genetic structure.

Active and passive surveillance for bat lyssaviruses in Italy revealed serological evidence for their circulation in three bat species.

The wide geographical distribution and genetic diversity of bat-associated lyssaviruses (LYSVs) across Europe suggest that similar viruses may also be harboured in Italian insectivorous bats. Indeed, bats were first included within the passive national surveillance programme for rabies in wildlife in the 1980s, while active surveillance has been performed since 2008. The active surveillance strategies implemented allowed us to detect neutralizing antibodies directed towards European bat 1 lyssavirus in six out of the nine maternity colonies object of the study across the whole country. Seropositive bats were Myotis myotis, M. blythii and Tadarida teniotis. On the contrary, the virus was neither detected through passive nor active surveillance, suggesting that fatal neurological infection is rare also in seropositive colonies. Although the number of tested samples has steadily increased in recent years, submission turned out to be rather sporadic and did not include carcasses from bat species that account for the majority of LYSVs cases in Europe, such as Eptesicus serotinus, M. daubentonii, M. dasycneme and M. nattereri. A closer collaboration with bat handlers is therefore mandatory to improve passive surveillance and decrypt the significance of serological data obtained up to now.

In artificial roost comparison, bats show preference for rocket box style.

Understanding microhabitat preferences of animals is critical for effective conservation, especially for temperate-zone bats, which receive fitness benefits from selecting optimal roost microhabitats. Artificial roost structures are increasingly being used in conservation efforts for at-risk bat species. To evaluate microhabitat differences in common artificial roost structures and determine if roost selection occurs based on structure type, we installed artificial roosts of three different styles (bat box, rocket box, and bark mimic) in six clusters. We compared size and measured temperature parameters (12 points/roost) while bats were excluded from one cluster. We simultaneously conducted census counts during the active season at five more clusters open to bats for 1–2 years. The rocket box style provided larger entrance area, surface area, and volume versus other roost types. Microclimate varied with roost design. More positions inside the bat box and rocket box stayed within critical temperature limits for bats (0–45°C)—i.e., were usable. The bark-mimic provided less usable space than the rocket box and, often, large proportions of the roost were > 45°C. The rocket box provided the widest temperature availability in a given hour (max range available 7°C) and was more stable than the bark mimic. A maternity colony of Indiana bats (Myotis sodalis) selected the rocket box style; four of five available rocket boxes became primary maternity roosts, with 2–210 bats emerging per night. Future work should aim to manipulate roost size, temperature availability, and temperature stability in isolation to identify which features drive roost microhabitat selection by bats. Comparative studies of artificial roosts account for some inherent irregularity in natural systems, allowing us to study the dynamics of roost microhabitats. We recommend season-long monitoring of microhabitat in novel artificial refuges and comparative studies of artificial and natural roosts, and urge managers to consider potential positive and negative effects when substituting artificial roosts for natural habitat.

Relatedness, parentage, and philopatry within a Natterer\u2019s bat (Myotis nattereri) maternity colony

Given their cryptic behaviour, it is often difficult to establish kinship within microchiropteran maternity colonies. This limits understanding of group formation within this highly social group. Following a concerted effort to comprehensively sample a Natterer’s bat (Myotis nattereri) maternity colony over two consecutive summers, we employed microsatellite DNA profiling to examine genetic relatedness among individuals. Resulting data were used to ascertain female kinship, parentage, mating strategies, and philopatry. Overall, despite evidence of female philopatry, relatedness was low both for adult females and juveniles of both sexes. The majority of individuals within the colony were found to be unrelated or distantly related. However, parentage analysis indicates the existence of a number of maternal lineages (e.g., grandmother, mother, or daughter). There was no evidence suggesting that males born within the colony are mating with females of the same colony. Thus, in this species, males appear to be the dispersive sex. In the Natterer’s bat, colony formation is likely to be based on the benefits of group living, rather than kin selection.

Maternity colonies of Myotis brandtii in the Polesie State Radiation-Ecological Reserve

Maternity colonies of Myotis brandtii in the Polesie State Radiation-Ecological Reserve

Landscape Characteristics Related to Use of Artificial Roosts by Northern Long-Eared Bats in North-Central West Virginia

In the eastern US, research is needed on the establishment and evaluation of conservation measures for forest-dwelling bats, in general, and for the newly listed Myotis septentrionalis (Northern Long-Eared Bat), in particular. Our objectives were to evaluate the overall use of 3 artificial roosting structures—rocket box, nursery box, and artificial bark—by bats and to relate this use to local landscape characteristics in north-central West Virginia. We monitored 306 structures during summer 2016 and detected use (i.e., presence of guano, visual identification, capture of bats) at 132 (43%) roosts, of which 55 (42%) were confirmed, through capture or visual identification, to contain Northern Long-eared Bats. Nursery boxes were used more than expected based on availability (60%), but rocket boxes accounted for 40 (73%) of the roosts confirmed to be occupied by Northern Long-eared Bats, with 70% being used by maternity colonies of this species. We utilized binomial generalized linear models and an information theoretic approach to examine use of artificial roosts by maternity colonies of Northern Long-eared Bats. Our best-supported model differentiating structures occupied by maternity colonies from those that housed individual bats showed relationships to elevation, slope, area solar radiation, and distance to streams and large (>200 ha) forests. Our study provides initial guidance for land and wildlife managers on implementing an effective conservation and management technique for bats within this region.

Population of hematophagous bats in the Andradina region, São Paulo: roost and control characterization

The present study quantified Desmodus rotundus population and characterized their roosts in the Andradina microregion, Sao Paulo, Brazil, in 2010 and 2012, determining the effect of bat control measures on roost numbers and types and their population. From April to June 2010, professionals from the Agriculture and Livestock Defense Coordination of the State of Sao Paulo responsible for the rabies control that consists of capturing and treating vampire bats with a vampiricide paste based on Warfarin 2%, inspected 50 bat roosts registered in 12 municipalities in the Andradina microregion, northwestern Sao Paulo. In September 2012, 31 of these roosts were again surveyed by the authors of this study. The vast majority (92% and 96% in 2010 and 2012, respectively) of the roosts were characterized as artificial, e.g., abandoned houses and warehouses, house attics, culverts under highways, deactivated wells and mills, bridges, disused housings, and barns. The only natural roosts found were tree hollows. The number of roosts and the bat population in roosts decreased drastically after the measures for direct control of hematophagous bats were performed, especially the number of maternity colonies, indicating that the direct selective method had a strong impact on reducing these populations.

Postnatal Growth and Vocalization Development in the Long-fingered Bat, Myotis capaccinii (Chiroptera, Vespertilionidae).

Robab Mehdizadeh, Hojjat Eghbali, and Mozafar Sharifi (2018) We simultaneously monitored postnatal growth and vocalization development in a free living population of the long-fingered bat, Myotis capaccinii, in a maternity colony in the Mahidasht cave, western Iran. Length of forearm and body mass of 1-day-old neonates averaged 19.59 ± 1.23 mm and 3.59 ± 0.23 g and followed linear pattern of growth at mean growth rates of 0.74 mm/day and 0.15 g/day until 28 days of age, after which is increased slowly. A similar nonlinear growth pattern was found for ten wing characteristics (wingspan, wing area, handwing length, handwing area, armwing length, armwing area, aspect ratio, wing loading, tip length ratio, and tip area ratio). However, postnatal growth followed a two phase linear pattern of increase-decrease for the epiphyseal-phalangeal gap and decrease- increase for wing loading. At birth, infant bats produced low, short frequency sonar and oral calls in isolation before they could open their eyes. Isolation calls obtained at age 1-4 days old from M. capaccinii pups were frequency modulated shallow calls with longer duration (7.54 ± 1.83 ms) and lower peak frequency (20.07 ± 0.89 kHz) compared to adult female calls (2.35 ± 0.75 ms and 54.02 ± 4.34 kHz). During days 12-16, calls began to resemble adult echolocation calls. Duration of calls increased slightly before 7 days old and then gradually decreased. The peak, start and end frequencies of spontaneous calls increased with age. When the juvenile bats started foraging outside the cave, they only omitted nasal FM calls with 1-2 harmonics. Comparing postnatal changes in body and wing characteristics with those of vocalization, we found that the most positive correlation was between body (forearm length and body mass) and wing features (wing area, wingspan, handwing area, armwing area and aspect ratio) and call parameters (peak, start and end frequency), while wing loading had a significant negative correlation with the call parameters.

Bat Community and Roost Site Selection of Tree-Dwelling Bats in a Well-Preserved European Lowland Forest

Worldwide species density of bats is highest in forests ecosystems. European primeval forests are now reduced to a few small and isolated patches because almost all forests are subject to management. Therefore, knowledge about bats in ancient and near-natural forests in Europe is scarce. In the well-preserved forest stands of the Belovezhskaya Pushcha National Park in Belarus we studied the bat community (1), the presence of maternity colonies and their preference in tree roost selection (2) and parameters of roosts used by forest dwelling bats (3). By mist-netting surveys, we identified 13 bat species and acoustic data suggested the presence of another three species. We detected 15 maternity colonies of seven bat species by radio-tracking reproductive females and 40 tree roosts within the forest. Roosts of Barbastella barbastellus, Pipistrellus pygmaeus and Plecotus auritus were almost exclusively behind the loose tree bark of decaying trees, or within narrow crevices. Myotis nattereri and Nyctalus leisleri showed a preference towards hollows (e.g., woodpecker-made cavities) within oak trees (Quercus robur). Our study shows that all tree-dwelling bat species are highly dependent on natural processes within forests that allow the formation of roost sites. Therefore, we strongly support that the natural aging process of trees, as well as the consequences of natural disturbance (e.g. through weather), should be permitted. This should extend beyond the protected zones of National Parks. In contrast, sanitary cuttings decrease the habitat's suitability for forest-dwelling bats. Finally, our results indicate that the forest complex of Belovezhskaya Pushcha and Białowieża is one of the most important bat areas in Europe.

Molecular detection of Anaplasma phagocytophilum DNA in the lesser horseshoe bat (Rhinolophus hipposideros) guano.

Although bats are increasingly recognised as potential reservoir hosts of human zoonotic pathogens, bacteria in bats are still poorly studied. To investigate the DNA faecal prevalence of the bacterium Anaplasma phagocytophilum, we sampled 23 lesser horseshoe bat (Rhinolophus hipposideros) maternity colonies located in buildings (churches, barns) in rural villages of eastern France. A total of 552 faecal samples were collected from 278 individuals. Anaplasma phagocytophilum DNA was detected in the faeces of 63 individuals (22.7%). Such high prevalence might suggest persistent infection in bats and/or a frequent consumption of insect preys carrying bacteria. Faecal DNA prevalence varied highly among colonies but was not related to the colony size. Faecal DNA prevalence was the highest in the Jura Department, where the density of ticks is known to be the highest across the study area. Because the sampled bats live in close proximity to humans, we discuss how concerning the presence of A. phagocytophilum DNA in bat guano is for humans frequenting places of worship that shelter bats. We also advocate future research to understand what a high faecal DNA prevalence in bat guano really implicates in terms of bacteria transmission.

Maternity Roosts of Townsend's Big-Eared Bats in Lava Tube Caves of Southern Idaho

Bats are being impacted by many threats (e.g., human disturbance of maternity roost sites and white-nose syndrome). Bat maternity roosts are a limited resource, and bats exhibit strong fidelity to these sites; therefore, identifying these features and conserving the surrounding habitat are important for bat management. Southern Idaho consists of the largest, contiguous volcanic pseudokarst area in the U.S., which provides important cave habitat for bats, but little is known about bat maternity roosts in this area. We compiled data spanning 36 years in southern Idaho to identify caves used by maternity colonies. From June 1980 to August 2016, researchers surveyed 313 caves. We documented 11 caves used by maternity colonies of Townsend's big-eared bats (Corynorhinus townsendii), and 10 caves that were potentially used by maternity colonies. In the 11 caves used as maternity roosts, the median number of Townsend's big-eared bats was 38, and the mean number was 49 individuals (SD = 47.1, range = 8 to 160 bats). Our data highlight southern Idaho as an important maternity roosting area for bats in Idaho and western North America, and provide baseline information of maternity caves prior to the arrival of white-nose syndrome, which can help managers during land-use planning in this area.

Restoration of Legacy Trees as Roosting Habitat for Myotis Bats in Eastern North American Forests

Most eastern North American Myotis roost in forests during summer, with species forming maternity populations, or colonies, in cavities or crevices or beneath the bark of trees. In winter, these bats hibernate in caves and are experiencing overwinter mortalities due to infection from the fungus Pseudogymnoascus destructans, which causes white-nose syndrome (WNS). Population recovery of WNS-affected species is constrained by the ability of survivors to locate habitats suitable for rearing pups in summer. Forests in eastern North America have been severely altered by deforestation, land-use change, fragmentation and inadvertent introduction of exotic insect pests, resulting in shifts in tree distributions and loss of large-diameter canopy-dominant trees. This paper explores patterns in use of tree roosts by species of Myotis across Canada and the United States using meta-data from published sources. Myotis in western Canada, the Northwest, and Southwest selected the largest diameter roost trees and also supported the largest maximum exit counts. Myotis lucifugus, M. septentrionalis and M. sodalis, three species that inhabit eastern forests and which are currently experiencing region-wide mortalities because of WNS, selected roosts with the smallest average diameters. Recovery efforts for bark- and cavity-roosting Myotis in eastern North American forests could benefit from management that provides for large-diameter trees that offer more temporally-stable structures for roosting during the summer maternity season.

Effect of intrinsic and extrinsic factors on the variability of echolocation pulses of Myotis nigricans (Schinz, 1821) (Chiroptera: Vespertilionidae)

Bats may exhibit plasticity in echolocation pulses as response to intrinsic and extrinsic factors, and the estimation of the magnitude of such variation can provide confidence in acoustic monitoring. Myotis nigricans (Schinz, 1821) is a widely distributed but relatively understudied Neotropical species for which, during fieldwork, we found maternity colonies in the Lagunas de Montebello National Park, in Chiapas, South-east Mexico, and no previous information in the area. Therefore, we aimed to provide an acoustic characterization on the basis of intraspecific variability for its recognition using bat detectors. For this purpose, we examined the moulding of shape, frequency-based and time-based acoustic parameters, specifically by the effect of age group (sub-adults vs. adults) and acoustic environment (open space vs. background vegetation). By graphic comparison of echolocation pulses between acoustic environments, we observed changes in shape by an increase in bandwidth and steeper modulation along background vegetation. Statistically, on univariate basis, we did not find a significant effect of age group, but we did of acoustic environment, specifically on highest frequency (higher average), duration (shorter average) and interpulse interval (shorter average) along background vegetation. On multivariate basis, we confirmed shorter average interpulse interval along background vegetation. The overall classification accuracy was relatively high (82.22%): 80% in open space and 84% along background vegetation. Our work reinforces previous knowledge about sound constraints imposed by vegetation clutter, and provides a reliable framework for acoustic monitoring of this species across structurally variable, and hence acoustically variable, environments in the area.

Population structure of the Townsend’s big-eared bat (Corynorhinus townsendii townsendii) in California

Townsend's big-eared bat (Corynorhinus townsendii townsendii) is a wide-ranging subspecies found throughout the western United States. Of the 5 subspecies currently recognized within C. townsendii, 2 are federally endangered and 2 others are considered species of concern. In California, C. t. townsendii is a species of concern given its loss of habitat and presumed limited dispersal capabilities. Here, we investigated the genetic structure and diversity of a group of maternity colonies across the Inyo-White Mountains in west-central California. Analysis of both nuclear (microsatellite loci) and mitochondrial (D-loop fragment) data show a lack of structure across the study region and significant isolation-by-distance, supporting gene flow among maternity colonies in a stepping stone pattern. The maternity colonies in our sampling region are thus part of 1 genetically healthy, panmictic population. Despite the overall genetic viability of C. t. townsendii in this region, we suggest maintaining the connection between colonies is a crucial step in the management and persistence of the subspecies.

An experimental test of effects of ambient temperature and roost quality on aggregation by little brown bats (Myotis lucifugus)

Environmental factors, such as ambient temperature (Ta) or roost/nest quality, can influence social behaviour of small-bodied endotherms because individuals may aggregate for social thermoregulation when Ta is low or select the warmest possible sites for roosting. Female temperate bats form maternity colonies in spring to communally raise pups and exploit social thermoregulation. They also select roosts with warm microclimates because low roost temperature (Troost) delays juvenile development. We studied captive female little brown bats (Myotis lucifugus) to test the hypothesis that variation in Ta and Troost influence social group size. First, we predicted that female bats would preferentially select artificially heated roosts over unheated roosts. Second, we predicted that, as Ta decreased, group size would increase because bats would rely more heavily on social thermoregulation. Third, we predicted that experimentally increasing Troost (i.e., roost quality) above Ta would result in larger group sizes due to greater aggregation in high quality roosts. We captured 34 females from a maternity colony and housed them in a flight-tent provisioned with four bat boxes. Each box was outfitted with a heating pad and thermostat. Over the course of eight-days we heated each roost box in sequence to near thermoneutral Troost for two days. Bats preferentially selected heated roosts over unheated roosts but, contrary to our prediction, group size decreased when Troost was much greater than Ta (i.e., when the benefits of a warm roost should have been highest). Our results suggest that social thermoregulation and the availability of warm roosts influence aggregation in bats and have implications for the potential of summer habitat protection and enhancement to help bat populations in the face of threats like white-nose syndrome.

Observed Resiliency of Little Brown Myotis to Long-Term White-Nose Syndrome Exposure

Abstract White-nose syndrome (WNS) is a disease that has killed millions of bats in eastern North America and has steadily been spreading across the continent. Little brown myotis Myotis lucifugus populations have experienced extensive declines; however, some localized populations have remained resilient, with bats surviving multiple years past initial WNS exposure. These persistent populations may be critical to species recovery, and understanding mechanisms leading to this long-term survival and persistence may provide insight into overall bat and disease management. We monitored a maternity colony of little brown myotis on Fort Drum Military Installation in northern New York between 2006 and 2017 to determine basic demographic parameters and find evidence of what may be leading to resiliency and persistence at this site. Total colony size declined by approximately 88% from 2008 to 2010 due primarily to impacts of WNS. Counts of all adults returning to the colony stabilized during 2010–2014 (mean = 94, range 84–101) and increased after 2014 (mean = 132, range = 108–166). We captured 727 little brown myotis (575 females, 152 males) and banded 534 individuals (389 females, 145 males) at the colony. The majority of sampled bats showed evidence of recent past WNS infection and exposure to Pseudogymnoascus destructans, and we documented pervasive presence and limited viability of the fungus within the colony's main roosting structure. We recaptured 98 individually marked females in years after initial banding, and some individuals survived at least 6 y. Ninety-one percent of all adult females, 93% of recaptured bats, and 90% of 1-y-old females (i.e., bats recaptured the first year after initial capture as juveniles) showed evidence of reproduction during the monitoring period. Using mark–recapture models, we estimated annual survival rates of juvenile and adult little brown myotis during 2009–2016 and examined whether reproductive condition or evidence of recent infection of WNS had any effect on survival. Annual survival rates were similar between juveniles and adults, but highly variable, ranging from 41.0 to 86.5%. Models indicated that neither evidence of recent past exposure to WNS nor reproductive status were related to survival. No one parameter stood out as being responsible for this colony's continued existence, and it is likely that many interwoven factors were responsible for the observed resilience. Although relatively high reproductive effort from all females (i.e., both1-y-old and >1-y-old ) and intermittently suitable survival rates have led to the continued persistence of, and population increases in, this summer colony, mortality from WNS and inherently low reproductive potential still seemed to be limiting population growth. Until there is a better understanding of this overall potential resiliency in little brown myotis, we recommend considering minimizing disturbance and direct human involvement within these persisting populations to allow whatever natural recovery that may be occurring to evolve uninterrupted.

Ongoing changes in migration phenology and winter residency at Bracken Bat Cave.

Bats play an important role in agroecology and are effective bioindicators of environmental conditions, but little is known about their fundamental migration ecology, much less how these systems are responding to global change. Some of the world's largest bat populations occur during the summer in the south-central United States, when millions of pregnant females migrate from lower latitudes to give birth in communal maternity colonies. Despite a relatively large volume of research into these colonies, many fundamental questions regarding their abundance-including their intra- and interseasonal variability-remain unanswered, and even estimating the size of individual populations has been a long-running challenge. Overall, monitoring these bat populations at high temporal resolution (e.g., nightly) and across long time spans (e.g., decades) has been impossible. Here, we show 22 continuous years of nightly population counts at Bracken Cave, a large bat colony in south-central Texas, enabling the first climate-scale phenological analysis. Using quantitative radar monitoring, we found that spring migration and the summer reproductive cycle have advanced by approximately 2weeks over the study period. Furthermore, we quantify the ongoing growth of a newly-established overwintering population that indicates a system-wide response to changing environmental conditions. Our observations reveal behavioral plasticity in bats' ability to adapt to changing resource availability, and provide the first long-term quantification of their response to a changing climate. As aerial insectivores, these changes in bat phenology and propensity for overwintering indicate probable shifts in prey availability, with clear implications for pest management across wider regional agrisystems.

Seasonal and Sexual Variation in Metabolism, Thermoregulation, and Hormones in the Big Brown Bat (Eptesicus fuscus)

In response to seasonal variation in energy availability and thermal environment, physiological and endocrine mechanisms have evolved in temperate zone animals. Seasonal changes in hormone activity affect metabolism, body temperature, and reproductive activity. We examined the seasonal regulatory role of hormones on basal metabolic rate (BMR) and regulatory nonshivering thermogenesis (RNST) in 98 female and 17 male adult Eptesicus fuscus (big brown bat). We measured BMR, RNST, and plasma levels of thyroid hormone (T3), leptin, and cortisol in bats captured in maternity colonies in eastern Massachusetts from May to August (from arousal from the hibernation phase to the prehibernation phase). We hypothesized that all three hormones are seasonally primarily metabolic hormones and secondarily thermogenic hormones. In males, only BMR significantly changed seasonally. In females, all five variables significantly changed seasonally. The seasonal pattern of plasma leptin and cortisol levels correlated with the seasonal pattern of BMR, with an initial increase followed by a decrease, suggesting that leptin and cortisol are primarily metabolic hormones. The seasonal pattern of plasma T3 levels generally paralleled the basic seasonal pattern of RNST, with both increasing at the second half of the season, suggesting that T3 is primarily a thermogenic hormone. The observed decrease in plasma leptin levels may be necessary to allow for the observed seasonal decrease in BMR, with the similar cortisol pattern important for leptin regulation. While T3 is needed to maintain BMR, it may play a more critical role in the seasonal regulation of RNST than of BMR.

High-Resolution MaxEnt Modelling of Habitat Suitability for Maternity Colonies of the Barbastelle Bat Barbastella barbastellus (Schreber, 1774) in Rhineland-Palatinate, Germany

The barbastelle bat Barbastella barbastellus (Schreber, 1774), probably one of the rarest of western European bat species, has suffered from substantial population declines over the last several decades. In fact, it was believed to be extinct within the federal state of Rhineland-Palatinate (western Germany) until the discovery of a maternity colony in 2004. More reproduction sites have since been found, which demonstrates a substantial knowledge gap about the actual distribution and abundance of the species in Rhineland-Palatinate. Suitable habitats for maternity colonies are crucial for the survival of a population and knowledge of their location is critical for conservation. We modelled the suitability of habitats for use by maternity colonies in Rhineland-Palatinate based on high-resolution data of the forest structure and roosting sites of maternity colonies, using the presence-only machine learning approach MaxEnt. In addition to statistical tests of the model performance, we analysed general occurrence surveys from the last few years for evidence of barbastelle and conducted an in-situ survey on one of the sites identified as highly suitable by the model, but for which no occurrence records exist. On this site, we discovered a new maternity colony. Analysis of third-party surveys resulted in two recently discovered colonies, which shows the barbastelle's range is not restricted to the area south of the Moselle River. The results of our study along with the scattered pattern of potentially suitable locations for maternity colonies in the region challenge previous assumptions of the geographic distribution of barbastelle in Rhineland-Palatinate. This study demonstrates the potential of habitat suitability modelling in conservation ecology and the results may provide a basis for future preservation strategies in the region.

How Do Young Bats Find Suitable Swarming and Hibernation Sites? Assessing the Plausibility of the Maternal Guidance Hypothesis Using Genetic Maternity Assignment for two European Bat Species

In many temperate zone bat species, large numbers of individuals aggregate in autumn at potential hibernacula such as caves, mines, and cellars, for a behaviour known as swarming. This autumn swarming probably serves two functions, the achievement of matings and the assessment of potential hibernation sites. Even though this remarkable behaviour has attracted a lot of research during the last decades, several central questions regarding the autumn swarming of temperate zone bats remain unanswered. One of them is how juvenile bats (defined here as young of the year) are able to find swarming sites, which are typically dozens of kilometres away from the maternity colonies where they had been born. In this study, we used a combination of field data and population genetic tools to assess whether the juveniles are likely to learn the location of swarming sites from their mothers. To obtain non-destructive wing-tissue samples for DNA-based maternity assignments, 170 Myotis daubentonii and 195 Myotis nattereri were captured during the swarming seasons in two subsequent years, at a large hibernaculum in Germany. Based on 14, respectively 13, highly polymorphic microsatellite loci, maternity assignment tests were conducted for all captured adult females and juveniles that had been born in the two respective years. For M. daubentonii we found four assigned mother-offspring pairs, whereas in M. nattereri, eight mother-offspring pairs could be assigned with high certainty. Moreover, among the latter species, in seven pairs the mothers and the assigned offspring were caught within ten minutes of one another on the same night. Using a simulation, we show that for M. nattereri, significantly more juveniles than expected are caught together with their mothers at the hibernacula. We discuss the implications of our findings with regard to understanding autumn swarming behaviour in temperate zone bats, as well as for the conservation of bats that depend on swarming sites for mating and hibernation.