Swarming of Bats at Different Elevations in the Carpathian Mountains

Karyotypic stasis and swarming influenced the evolution of viral tolerance in a species-rich bat radiation

The emergence of COVID-19 and severe acute respiratory syndrome (SARS) has prioritized understanding bats' viral tolerance. Myotis bats are exceptionally species rich and have evolved viral tolerance. They also exhibit swarming, a cryptic behavior where large, multi-species assemblages gather for mating, which has been hypothesized to promote interspecific hybridization. To resolve the coevolution of genome architecture and their unusual antiviral tolerance, we undertook a phylogenomic analysis of 60 Old World Myotis genomes. We demonstrate an extensive history of introgressive hybridization that has replaced the species phylogeny across 17%-93% of the genome except for pericentromeric regions of macrochromosomes. Introgression tracts were enriched on microchromosome regions containing key antiviral pathway genes overexpressed during viral challenge experiments. Together, these results suggest that the unusual Myotis karyotype may have evolved to selectively position immune-related genes in high recombining genomic regions prone to introgression of divergent alleles, including a diversity of interleukin loci responsible for the release of pro-inflammatory cytokines.

Bats at an Altitude above 2000 m on Pirin Mountain, Bulgaria

The study describes a pilot survey on bats in the highest areas of Pirin Mountain. The methods included examining subfossil bone remains, mist-netting, and recording echolocation calls. The study was conducted in August 2002 and 2013 and from 2019 to 2020. While in general, bat diversity tends to decrease with increasing altitude due to harsher environmental conditions, the present study, despite a short period, reveals high diversity. Twenty species, more than half of the Bulgarian bat fauna, were detected. The recording and analysis of vocal signatures proved to be the best way to inventory bat diversity. At least 13 species were detected by this method. Vespertilio murinus and Tadarida teniotis together make up more than 60% of all reliably determined echolocation sequences. Significant activity was found for Myotis myotis/blythii, Plecotus auritus, Eptesicus serotinus, and E. nilssonii. The registration of the latter species is of considerable faunistic interest. It was previously only known from a single specimen at one location in the country. The sex and age structure of the bat assemblage suggests that it is likely a swarming assemblage. The area is the highest swarming location in Europe. The results provide valuable information on bat ecology and behaviour, which can be used to inform management and protection efforts.

Changing with the times: Seasonal environmental gradients unveil dynamic bat assemblages and vulnerability

Uncovering the temporal and spatial dynamics of biological communities in response to biotic and abiotic drivers is essential to predict the effects of environmental change on biodiversity. Similarly, estimating species vulnerability in the face of such dynamics is crucial for implementing effective conservation actions. We explored how bat diversity changes over the year across an altitudinal gradient and identified the environmental drivers that shape bat communities. By analysing species' marginality within the biophysical niche space, we evaluated bats' vulnerability to foreseeable environmental changes. Our results suggest that altitude, the proportion of forest cover and shrub cover are the main drivers shaping bat communities year-round. Additionally, while some bat species are restricted to a single ecological assemblage (or ecological preferences group), others show greater plasticity throughout the year. Importantly, we found that although bats associated with highland habitats and forests could be particularly vulnerable to environmental changes (in particular Myotis mystacinus), this vulnerability correlates poorly with their national conservation status. We suggest that species' ecological plasticity is critical for the resilience of biological communities exposed to environmental changes and should be considered when planning tailored conservation strategies.

Prehibernation swarming in temperate bats: a critical transition between summer activity and hibernation

In this contribution to Dr. Brock Fenton's Festschrift, we briefly reflect on Dr. Fenton's seminal works examining bat swarming behaviour in Ontario and use these reflections as a launch pad to conduct a global review on autumn swarming in bats, and underlying hypotheses to explain this behaviour. Our review frames the swarming period as a time of critical transitions, during which bats must balance multiple life history trade-offs, and we consider how various intrinsic and extrinsic factors may contribute to inter- and intraspecific differences in autumn behaviour. We discuss the transition away from summer residency, including maternity colony breakup, day roosting, and migration during autumn. We review key life history elements of swarming, including mating behaviours and associated reproductive condition, genetic exchange during swarming, and variation among sexes, ages, and species. Finally, we discuss the behaviours and physiological states of bats transitioning from the swarming period to hibernation. Throughout, we identify common patterns and also exceptions. Over 50 years of research has yielded many insights into autumn swarming, but knowledge gaps remain. Future research focus on a greater diversity of species will reveal general principles underlying the transition from summer active season, through the swarming period, and into winter hibernation.

A population in perpetual motion: Highly dynamic roosting behavior of a tropical island endemic bat

Although island endemic bats are a source of considerable conservation concerns, their biology remains poorly known. Here, we studied the phenology and roosting behavior of a tropical island endemic species: the Reunion free-tailed bat (Mormopterus francoismoutoui). This widespread and abundant species occupies various natural and anthropogenic environments such as caves and buildings. We set up fine-scale monitoring of 19 roosts over 27 months in Reunion Island and analyzed roost size and composition, sexual and age-associated segregation of individuals, as well as the reproductive phenology and body condition of individuals. Based on extensive data collected from 6721 individuals, we revealed a highly dynamic roosting behavior, with marked seasonal sex-ratio variation, linked to distinct patterns of sexual aggregation among roosts. Despite the widespread presence of pregnant females all over the island, parturition was localized in a few roosts, and flying juveniles dispersed rapidly toward all studied roosts. Our data also suggested a 7-month delay between mating and pregnancy, highlighting a likely long interruption of the reproductive cycle in this tropical bat. Altogether, our results suggest a complex social organization in the Reunion free-tailed bat, with important sex-specific seasonal and spatial movements, including the possibility of altitudinal migration. Bat tracking and genetic studies would provide additional insights into the behavioral strategies that shape the biology of this enigmatic bat species. The fine-scale spatiotemporal data revealed by our study will serve to the delineation of effective conservation plans, especially in the context of growing urbanization and agriculture expansion in Reunion Island.

Distribution, Dominance Structure, Species Richness, and Diversity of Bats in Disturbed and Undisturbed Temperate Mountain Forests

The increase in mean annual temperature and reduction in summer rainfall from climate change seem to increase the frequency of natural and human-made disturbances to forest vegetation. This type of rapid vegetation change also significantly affects bat diversity. The aim of our study was to document differences in the ecological parameters of bat assemblages in different types of temperate mountain forests, particularly between disturbed and undisturbed coniferous and deciduous forests. Additionally, these issues were considered along an elevation gradient. We mist netted bats on 73 sites, between 931 and 1453 m elevation, in the forests of the Tatra Mountains in southern Poland. During 2016–2020, 745 bats, representing 15 species, were caught. The most abundant were Myotis mystacinus (Kuhl, 1817) (53.0%) and M. brandtii (Eversmann, 1845) (21.5%). We observed differences in species diversity, elevational distribution, and dominance between different types of forests and forest zones. Species richness peaked at around 1000–1100 m elevation. The highest species richness and other indices were observed in undisturbed beech stands, although they constituted only about 2.7% of the forest area. The lowest species diversity was observed in disturbed coniferous forests, in both the lower and upper forest zone. The species richness and dominance structure of bat assemblages were also found to depend on the location above sea level. In some bat species, the sex ratio was higher at higher elevations, and differences in the sex ratio in a few bat species, between different types of forests, were observed. Our findings suggest that disturbed, beetle-killed spruce forests are an unsuitable environment for some bat species.

The Use of Intrinsic Markers for Studying the Migratory Movements of Bats

Mortality of migratory bat species at wind energy facilities is a well-documented phenomenon, and mitigation and management are partially constrained by the current limited knowledge of bat migratory movements. Analyses of biochemical signatures in bat tissues ("intrinsic markers") can provide information about the migratory origins of individual bats. Many tissue samples for intrinsic marker analysis may be collected from living and dead bats, including carcasses collected at wind energy facilities. In this paper, we review the full suite of available intrinsic marker analysis techniques that may be used to study bat migration, with the goal of summarizing the current literature and highlighting knowledge gaps and opportunities. We discuss applications of the stable isotopes of hydrogen, oxygen, nitrogen, carbon, sulfur; radiogenic strontium isotopes; trace elements and contaminants; and the combination of these markers with each other and with other extrinsic markers. We further discuss the tissue types that may be analyzed for each and provide a synthesis of the generalized workflow required to link bats to origins using intrinsic markers. While stable hydrogen isotope techniques have clearly been the leading approach to infer migratory bat movement patterns across the landscape, here we emphasize a variety of lesser used intrinsic markers (i.e., strontium, trace elements, contaminants) that may address new study areas or answer novel research questions.

Optimizing bat bioacoustic surveys in human-modified Neotropical landscapes

During the last decades, the use of bioacoustics as a non-invasive and cost-effective sampling method has greatly increased worldwide. For bats, acoustic surveys have long been known to complement traditional mist-netting, however, appropriate protocol guidelines are still lacking for tropical regions. Establishing the minimum sampling effort needed to detect ecological changes in bat assemblages (e.g., activity, composition, and richness) is crucial in view of workload and project cost constraints, and because detecting such changes must be reliable enough to support effective conservation management. Using one of the most comprehensive tropical bat acoustic data sets, collected in the Amazon, we assessed the minimum survey effort required to accurately assess the completeness of assemblage inventories and habitat selection in fragmented forest landscapes for aerial insectivorous bats. We evaluated a combination of 20 different temporal sampling schemes, which differed regarding number of hours per night, number of nights per site, and sampling only during the wet or dry season, or both. This was assessed under two different landscape scenarios: in primary forest fragments embedded in a matrix of secondary forest and in the same forest fragments, but after they had been re-isolated through clearing of the secondary forest. We found that the sampling effort required to achieve 90% inventory completeness varied considerably depending on the research aim and the landscape scenario evaluated, averaging ~80 and 10 nights before and after fragment re-isolation, respectively. Recording for more than 4 h per night did not result in a substantial reduction in the required number of sampling nights. Regarding the effects of habitat selection, except for assemblage composition, bat responses in terms of richness, diversity, and activity were similar across all sampling schemes after fragment re-isolation. However, before re-isolation, a minimum of four to six sampling hours per night after dusk and three to five nights of sampling per site were needed to detect significant effects that could otherwise go unnoticed. Based on our results, we propose guidelines that will aid to optimize sampling protocols for bat acoustic surveys in the Neotropics.

The northernmost findings of the Alcathoe bat (Myotis alcathoe von Helversen & Heller, 2001) in Poland

The Alcathoe bat Myotis alcathoe (von Helversen, Heller, 2001) is a newly described species of the cryptic complex of whiskered bat species living in sympatry across Europe. The habitats preferred by this species are natural, moist and deciduous forests with old trees and water streams. The majority of known locations of this species come from highlands, foothills and mountainous regions while practically not occurring in the lower elevations. They come mainly from cave areas, where bats were caught during autumn swarming, while records in other seasons are much less frequent. Currently, individual sites in Poland also come from lowlands, beyond the range of the mountains and uplands, which indicates a possible wider range of this species. The bats were captured using mist-nests in the Silesian Lowlands for three consecutive years (2013–2015). The localities were placed in various forest environments, ranging in elevation from 100 to 260 m a.s.l. Bats were initially identified based on morphological features, then the correctness of identification was confirmed by molecular methods. Two females and five males of Myotis alcathoe were captured into four new locations from the lowlands of Poland: Przemków, Głębowice, Chodlewo, and Dalkowskie Jary (Silesian Lowland). Old trees and a small watercourse were important elements in all these locations. Currently, these findings are the northernmost locations of the species in Poland and one of the northernmost locations in Central Europe. The latest findings of the species are located about 50 km to the south, but the vast majority of the rest of locations is from the foothills belt. This finding suggests that the species may inhabit regions much further north than previously suggested, and the limiting factor is the presence of old trees in wet environments.

Phenology of reproductive condition varies with age and spring weather conditions in male Myotis daubentonii and M. nattereri (Chiroptera: Vespertilionidae)

We examine the extent to which intrinsic and extrinsic factors influence reproductive phenology in male bats at the population level. Using data from thirteen breeding seasons (2006-2018), encompassing the reproductive histories of 1546 Myotis daubentonii and 530 M. nattereri males, we compare rates of sexual maturation and the temporal distribution of phases of spermatogenesis between juvenile (born that season) and adult (born in previous seasons) males. We found that (i) higher proportions of M. daubentonii (50.81%) than M. nattereri (12.85%) became sexually mature as juveniles, (ii) the proportion of juveniles in reproductive condition per annum was influenced by spring weather conditions, (iii) in both species males that reached puberty as juveniles had higher body mass, on average, than immature juveniles, (iv) older males (aged ≥4 years old) commenced spermatogenesis earlier than young adult males (aged 1-3 years old), whilst juveniles that commenced spermatogenesis did so later in the year than adults, in both species, and (v) M. daubentonii commenced and completed spermatogenesis earlier than M. nattereri in the equivalent age class. Our findings suggest that selection pressure exists for early mating readiness and synchronisation with female receptivity.

Bat fauna associated with artificial ponds in La Malinche National Park, a mountain ecosystem of Mexico

An increase in water demand in mountains has reduced its availability for the fauna. As conservation tools, artificial ponds can be used to offer water to animals. Many studies have assessed the use of ponds by bats. However, most of them have been concentrated in the United States and Europe, while in regions with higher bat diversity the information is scarce. We captured the bat species associated with artificial ponds in a Mexican mountain where water was intubated 25 years ago. We identified and analyzed the bats’ species proportion and sex ratio and evaluated if species richness and abundance were affected by season, mean monthly precipitation, maximum monthly temperature and maximum monthly humidity. We captured 90 bats of seven species (Vespertilionidae), where

Host social organization and mating system shape parasite transmission opportunities in three European bat species

For non-mobile parasites living on social hosts, infection dynamics are strongly influenced by host life history and social system. We explore the impact of host social systems on parasite population dynamics by comparing the infection intensity and transmission opportunities of three mite species of the genus Spinturnix across their three European bat hosts (Myotis daubentonii, Myotis myotis, Myotis nattereri) during the bats’ autumn mating season. Mites mainly reproduce in host maternity colonies in summer, but as these colonies are closed, opportunities for inter-colony transmission are limited to host interactions during the autumn mating season. The three investigated hosts differ considerably in their social system, most notably in maternity colony size, mating system, and degree of male summer aggregation. We observed marked differences in parasite infection during the autumn mating period between the species, closely mirroring the predictions made based on the social systems of the hosts. Increased host aggregation sizes in summer yielded higher overall parasite prevalence and intensity, both in male and female hosts. Moreover, parasite levels in male hosts differentially increased throughout the autumn mating season in concordance with the degree of contact with female hosts afforded by the different mating systems of the hosts. Critically, the observed host-specific differences have important consequences for parasite population structure and will thus affect the coevolutionary dynamics between the interacting species. Therefore, in order to accurately characterize host-parasite dynamics in hosts with complex social systems, a holistic approach that investigates parasite infection and transmission across all periods is warranted.

Autumn flight activity of the greater horseshoe bat at hibernacula

The activity patterns of vespertilionid bats at the entrances of hibernacula in temperate zones have been investigated on many occasions. However, little is known about nocturnal flight activity in autumn and its function in horseshoe bats so far. Here, we have recorded the autumn flight activity in and around the entrances of hibernacula of greater horseshoe bats,Rhinolophus ferrumequinumby behavioural observations, mistnetting, and acoustic surveys for two consecutive years. Greater horseshoe bats not only chased each other around cave entrances but also entered and left the entrance frequently. However, no mating events were directly observed in this study, normally a prominent part of swarming behaviour in vespertilionids. Therefore, it is difficult to deduce the function of the autumn flight activity of the greater horseshoe bats at hibernacula from the present data. Additionally, the recorded flight activity was positively correlated with ambient temperature and humidity. To our knowledge, our study provides the first detailed record of the pattern of autumn flight activity in horseshoe bats, and suggests that weather conditions may impact the bats’ nocturnal flight activity.

Population genetic structure of a common host predicts the spread of white-nose syndrome, an emerging infectious disease in bats

Landscape complexity influences patterns of animal dispersal, which in turn may affect both gene flow and the spread of pathogens. White-nose syndrome (WNS) is an introduced fungal disease that has spread rapidly throughout eastern North America, causing massive mortality in bat populations. We tested for a relationship between the population genetic structure of the most common host, the little brown myotis (Myotis lucifugus), and the geographic spread of WNS to date by evaluating logistic regression models of WNS risk among hibernating colonies in eastern North America. We hypothesized that risk of WNS to susceptible host colonies should increase with both geographic proximity and genetic similarity, reflecting historical connectivity, to infected colonies. Consistent with this hypothesis, inclusion of genetic distance between infected and susceptible colonies significantly improved models of disease spread, capturing heterogeneity in the spatial expansion of WNS despite low levels of genetic differentiation among eastern populations. Expanding our genetic analysis to the continental range of little brown myotis reveals strongly contrasting patterns of population structure between eastern and western North America. Genetic structure increases markedly moving westward into the northern Great Plains, beyond the current distribution of WNS. In western North America, genetic differentiation of geographically proximate populations often exceeds levels observed across the entire eastern region, suggesting infrequent and/or locally restricted dispersal, and thus relatively limited opportunities for pathogen introduction in western North America. Taken together, our analyses suggest a possibly slower future rate of spread of the WNS pathogen, at least as mediated by little brown myotis.

Bats Swarm Where They Hibernate: Compositional Similarity between Autumn Swarming and Winter Hibernation Assemblages at Five Underground Sites

During autumn in the temperate zone of both the new and old world, bats of many species assemble at underground sites in a behaviour known as swarming. Autumn swarming behaviour is thought to primarily serve as a promiscuous mating system, but may also be related to the localization and assessment of hibernacula. Bats subsequently make use of the same underground sites during winter hibernation, however it is currently unknown if the assemblages that make use of a site are comparable across swarming and hibernation seasons. Our purpose was to characterize the bat assemblages found at five underground sites during both the swarming and the hibernation season and compare the assemblages found during the two seasons both across sites and within species. We found that the relative abundance of individual species per site, as well as the relative proportion of a species that makes use of each site, were both significantly correlated between the swarming and hibernation seasons. These results suggest that swarming may indeed play a role in the localization of suitable hibernation sites. Additionally, these findings have important conservation implications, as this correlation can be used to improve monitoring of underground sites and predict the importance of certain sites for rare and cryptic bat species.

Genetic connectivity among swarming sites in the wide ranging and recently declining little brown bat (Myotis lucifugus)

Characterizing movement dynamics and spatial aspects of gene flow within a species permits inference on population structuring. As patterns of structuring are products of historical and current demographics and gene flow, assessment of structure through time can yield an understanding of evolutionary dynamics acting on populations that are necessary to inform management. Recent dramatic population declines in hibernating bats in eastern North America from white-nose syndrome have prompted the need for information on movement dynamics for multiple bat species. We characterized population genetic structure of the little brown bat, Myotis lucifugus, at swarming sites in southeastern Canada using 9 nuclear microsatellites and a 292-bp region of the mitochondrial genome. Analyses of F ST, ΦST, and Bayesian clustering (STRUCTURE) found weak levels of genetic structure among swarming sites for the nuclear and mitochondrial genome (Global F ST = 0.001, P < 0.05, Global ΦST = 0.045, P < 0.01, STRUCTURE K = 1) suggesting high contemporary gene flow. Hierarchical AMOVA also suggests little structuring at a regional (provincial) level. Metrics of nuclear genetic structure were not found to differ between males and females suggesting weak asymmetries in gene flow between the sexes. However, a greater degree of mitochondrial structuring does support male-biased dispersal long term. Demographic analyses were consistent with past population growth and suggest a population expansion occurred from approximately 1250 to 12,500 BP, following Pleistocene deglaciation in the region. Our study suggests high gene flow and thus a high degree of connectivity among bats that visit swarming sites whereby mainland areas of the region may be best considered as one large gene pool for management and conservation.

The patterns of seasonal activity of Ixodes vespertilionis (Acari: Ixodidae) on Rhinolophus hipposideros in nursery colonies

The aim of this study was to describe the dynamics of the long-legged bat tick Ixodes vespertilionis infestation on the lesser horseshoe bat Rhinolophus hipposideros in 2 nursery colonies roosting in attics. Out of a total of 810 lesser horseshoe bats examined, 217 (26.8%) were found to be infested with a total of 464 I. vespertilionis individuals. The developmental stage most frequently found was the larva, followed by the nymph, and the adult female. Bats were significantly more frequently infested with I. vespertilionis ticks in the period April to May than in other months. In these months, all tick developmental stages were observed. During summer and autumn, only immature developmental stages were recorded, whilst in September and October larvae predominated. Considerable differences in tick load between nursery colonies were observed. The length of seasonal presence on bats, prevalence, and infestation intensity of I. vespertilionis on lesser horseshoe bats were higher in the nursery colony situated in close vicinity of a cave than in the colony situated far from the caves. The results suggest that the pattern of seasonal infestation of ticks on bats roosting in nursery colonies coincides with the seasonal activity of Rh. hipposideros in the caves. The first case of mixed infestation of the lesser horseshoe bat with I. vespertilionis and I. ricinus were also recorded.

Nonlinear distribution pattern of hibernating bats in caves along an elevational gradient in mountain (Carpathians, Southern Poland)

Background

Thermal gradients along changes in elevation in mountainous environments are reflected by different biotas. Although there have been studies of elevation variation in bat assemblages in summer, winter changes in the same gradients remain unknown.

Methodology/Principal Findings

The objective of this study was to document changes in the species composition of bats hibernating in caves along a temperate elevational gradient. We studied 70 caves between from 300 m to 1,930 m altitude along a slope of the Carpathian Mountains in southern Poland. We recorded changes in bats, including species richness, abundance, altitudinal distribution and dominance during consecutive winters between 2003 and 2009. Similarity of dominance of faunal structure was assessed by using the Bray-Curtis similarity index. We used the generalised additive model and rarefaction to study the variation in species richness, and generalized additive mixed models to examine the effect of abiotic factors on the qualitative and quantitative structure of bat assemblages. During 351 surveys we recorded 13,856 hibernating bats from 15 species. Species richness peaked around mid-elevation (1,100–1,400 m a.s.l.) with richness declining at both higher and lower elevations. Based on the results of a cluster analysis, we could distinguish among four altitudinal zones that differed in species richness and dominance structure.

Conclusions/Significance

This is the first study documenting changes in species richness and variation of structure of bats hibernating in caves along an elevational gradient. The most surprising and key finding is the fact that changes in the structure of assemblages of hibernating bats along the altitudinal gradient occurred in jumps, forming zones similar to those observed in the vegetation zones. Moreover, species richness and dominance structure of assemblages of hibernating bats in the mountains depended not only on location above sea level, but also on local geomorphologic conditions which strongly affected the microclimate of the caves.

The bat fauna hibernating in the caves of the Polish Tatra Mountains, and its long-term changes

We monitored bats hibernating in the Tatra Mountains during winters between 1997 and 2012. The Tatras are Central Europe’s second-highest massif after the Alps. Our winter censuses identified 14 species of bats hibernating in caves of the Polish Tatras. The most characteristic features of these winter bat assemblages were the dominance of Myotis mystacinus and high numbers of Eptesicus nilssonii. During the monitoring period, we noted qualitative and quantitative changes in the hibernating bat fauna. Two thermophilous species not recorded earlier and absent during the entire Holocene appeared: Rhinolophus hipposideros and Myotis emarginatus. The abundance of M. mystacinus, M. daubentonii, E. nilssonii and Plecotus auritus increased. We found no such changes in the abundance of M. myotis or M. nattereri. The Tatra Mountains are a key region for the occurrence of bats of the mystacinus group (particularly M. mystacinus sensu stricto) in Europe, and for E. nilssonii an important region in Central Europe.

Hybridization hotspots at bat swarming sites

During late summer and early autumn in temperate zones of the Northern Hemisphere, thousands of bats gather at caves, mainly for the purpose of mating. We demonstrated that this swarming behavior most probably leads not only to breeding among bats of the same species but also interbreeding between different species. Using 14 nuclear microsatellites and three different methods (the Bayesian assignment approaches of STRUCTURE and NEWHYBRIDS and a principal coordinate analysis of pairwise genetic distances), we analyzed 375 individuals belonging to three species of whiskered bats (genus Myotis) at swarming sites across their sympatric range in southern Poland. The overall hybridization rate varied from 3.2 to 7.2%. At the species level, depending on the method used, these values ranged from 2.1-4.6% in M. mystacinus and 3.0-3.7% in M. brandtii to 6.5-30.4% in M. alcathoe. Hybrids occurred in about half of the caves we studied. In all three species, the sex ratio of hybrids was biased towards males but the observed differences did not differ statistically from those noted at the population level. In our opinion, factors leading to the formation of these admixed individuals and their relatively high frequency are: i) swarming behaviour at swarming sites, where high numbers of bats belonging to several species meet; ii) male-biased sex ratio during the swarming period; iii) the fact that all these bats are generally polygynous. The highly different population sizes of different species at swarming sites may also play some role. Swarming sites may represent unique hybrid hotspots, which, as there are at least 2,000 caves in the Polish Carpathians alone, may occur on a massive scale not previously observed for any group of mammal species in the wild. Evidently, these sites should be treated as focal points for the conservation of biodiversity and evolutionary processes.

Argasid and spinturnicid mite load on swarming bats in the Tatra Mountains, Poland

Altogether 445 bats, representing nine species, caught during swarming in the Lodowa Cave in Mount Ciemniak, Western Tatra Mountains, southern Poland, were examined for ectoparasitic mites. In total, 259 spinturnicid (Spinturnix mystacina, S. andegavinus, S. kolenatii, S. plecotinus and S. myoti) and 95 argasid (Carios vespertilionis) mites were collected from seven bat species, Myotis myotis, M. mystacinus, M. brandtii, M. daubentonii, Eptesicus nilssonii, Plecotus auritus, and Vespertilio murinus. There were sex-based differences in the prevalence of mites in some hosts but no differences in their mean intensity and there was no observed relationship between the number of mites and the condition of the bats. The prevalence of mites differed significantly between years in E. nilssonii. The results suggested a very low mite load on swarming bats that had no impact on the body condition of bats.