Roost Availability Research Articles

Perspectives on forestry management: How do bats fit in?

AbstractIn the last decade, bat conservation guidance has received increasing attention, as many United States bat species are in decline due to white‐nose syndrome and have been listed or considered for federal endangered species status. Research on how these species are impacted by forestry management decisions has advanced to provide specific conservation actions for these imperiled species. We set out to better understand the level of knowledge land managers had in relation to forestry techniques and their impact on wildlife conservation in order to more effectively strategize how we can efficiently provide educational resources. We surveyed 78 land managers in Illinois to identify their priorities for management and how familiar they were with forestry management guidelines for bat conservation. We followed up with a subset of voluntary participants with semistructured phone interviews to generate more in‐depth responses. Using these tools, we reveal that a top priority for most managers in Illinois is invasive species management. Most have some familiarity with bat conservation actions, but few were confident in their knowledge of threatened and endangered species. Thirteen of the twenty phone interviews identified a preference for talking to/hearing from experts to receive information on bat conservation. These results highlighted where there are information gaps on best practices for forestry management from a conservation perspective, and identified how we can best address these through partnerships with land managers. Implementation of these practices is likely how recovery of these vulnerable species will happen—through protection of their basic needs, including availability of roosts, abundance of prey, and access to uncontaminated water resources.

Patterns and correlates of potential range shifts of bat species in China in the context of climate change.

Climate change may diminish biodiversity; thus, it is urgent to predict how species' ranges may shift in the future by integrating multiple factors involving more taxa. Bats are particularly sensitive to climate change due to their high surface-to-volume ratio. However, few studies have considered geographic variables associated with roost availability and even fewer have linked the distributions of bats to their thermoregulation and energy regulation traits. We used species distribution models to predict the potential distributions of 12 bat species in China under current and future greenhouse gas emission scenarios (SSP1-2.6 and SSP5-8.5) and examined factors that could affect species' range shifts, including climatic, geographic, habitat, and human activity variables and wing surface-to-mass ratio (S-MR). The results suggest that Ia io, Rhinolophus ferrumequinum, and Rhinolophus rex should be given the highest priority for conservation in future climate conservation strategies. Most species were predicted to move northward, except for I. io and R. rex, which moved southward. Temperature seasonality, distance to forest, and distance to karst or cave were the main environmental factors affecting the potential distributions of bats. We found significant relationships between S-MR and geographic distribution, current potential distribution, and future potential distribution in the 2050s. Our work highlights the importance of analyzing range shifts of species with multifactorial approaches, especially for species traits related to thermoregulation and energy regulation, to provide targeted conservation strategies.

Spatiotemporal dynamics in the roosting ecology of the green toad: implications for urban planning and nature conservation

Continuously growing urbanisation and the ongoing rebuilding of urban habitats affect amphibians, the most threatened vertebrate groups. Even though the effects of urbanisation are mostly negative, some artificial components of the urban landscape may also display positive relationships with amphibian populations and therefore work in favour of their persistence in cities. Roosts provide protection from predation, desiccation and offer invertebrate prey availability; therefore, roost availability is an essential necessity of amphibian maintenance in urban areas. On the example of the European green toad Bufotes viridis, a typical urban dweller, we investigated roost-type occupancy and their distribution relative to a breeding pond during the active season (from June to October). The analysis was done with regard to the different life stages of individuals from three urban populations. Green toads used fissures situated in various man-made constructions (e.g., buildings, roads, pathways) for roosting cavities, however without any predominant pattern among toad life stages. The local architecture of the study sites mainly determined the type of occupied roosts. In adults and juveniles we recorded a gradually increased roost distance from breeding pond, while subadults were found roosting further from the water during the active season. Management measures aimed at maintaining a favourable state of green toad populations in urban environments should incorporate a complex of actions that consider general as well as the local ecological patterns of particular populations.

Identifying shorebird conservation hotspots and restoration gaps in stopover sites: A perspective of ‘ecologically linked’ habitats

Shorebird populations are declining around the world, which has prompted concerns regarding tidal flat protection during migration. The lack of high-tide roosts not only can limit the access of shorebirds to tidal flats but also means that they expend more energy when moving between tidal flats and roosting sites. This situation can negatively affect their body condition. This highlights the importance of maintaining a network of tidal flats and high-tide roosts “ecologically linked” by shorebirds. Using the Yellow River Delta (YRD), a key stopover site in the East Asian–Australasian Flyway (EAAF), as the case study area, we assessed how the availability of optimal high-tide roosts has changed over time and identified conservation hotspots and restoration gaps from the perspective of ecological connectivity for shorebirds. Based on a developed Geographic Information System (GIS) method, combined with knowledge of shorebird roost choices from the literature and remote sensing data, we evaluated the adequacy of high-tide roosts in the YRD over 20 years (2000–2020) and identified restoration areas by scenario analysis. The results showed that 1) the mean distance between potential intertidal habitats and the nearest optimal high-tide habitat increased from 1305 m in 2000 to 2931 m in 2020, with a 30 % decline in the area of intertidal habitats suitably covered by optimal high-tide habitats for shorebirds in Group 1 (body length ≦ 20 cm) in the YRD; 2) the scenario analysis suggested that this gap can be eliminated by seasonal management of mariculture ponds and salt pans in key areas. This approach is likely applicable to stopover sites throughout the EAAF.

Continuous low-intensity predation by owls (Strix aluco) on bats (Nyctalus lasiopterus) in Spain and the potential effect on bat colony stability.

Owls prey on bats, but information on owl predation is scarce, its impact on bat mortality is unclear, and reports on behavioural responses, including roost-switching and fission-fusion behaviour, are equivocal. To study the link between owl predation and anti-predator behaviour in bats, we evaluated seven months of video recordings at roosts and the behaviour of 51 passive integrated transponder (PIT)-tagged bats and bats without tags in a geographically isolated colony of greater noctule bats (Nyctalus lasiopterus) in Spain. We found the tawny owl Strix aluco to almost continuously hunt N. lasiopterus, from perches and on the wing, well after the bats emerged at dusk and when they returned to their roosts. We recorded 39 unsuccessful and three successful attacks. Nonetheless, we found no evidence that owl predation modifies bat behaviour. While the bats constituted only a very small proportion of the owls' diet, owl predation accounted for an estimated 30-40% of bat mortality, which may have a significant impact on small, local or isolated bat populations, in particular, and thereby shape regional bat distributions. We hypothesize that low roost availability may also affect the bats' potential response to predation, which could lead to natural predation having an excessive impact on bat populations.

The Influence of Roost Type and Diet on Energy Expenditure in Bats

Bats spend most of their lives resting, socializing, and raising their young in roosts. Roost conditions may affect the lifetime energy expenditure of bats, and this could, in turn, influence fitness of individuals. Different kinds of roosts impose different microclimatic conditions that can affect the thermal balances of bats that use them. Bats thermoregulate by using both physiological mechanisms (such as changes in conductance) and behavioral responses (huddling or active search of certain microclimates). We hypothesized that the contribution of these thermoregulatory strategies would differ depending on the roost type that bats use. To test this idea, we collated data from the literature on metabolic rate (MR), body temperature (Tb), ambient temperature at which MR and Tb were collected, roost type, and diet for 43 species of bats spanning eleven families. From these data, we calculated, for each species, the wet conductance and the area of the thermoregulatory polygon (TRP) as a proxy for the physiological thermoregulatory capabilities of bats. We found that, after controlling for phylogeny, wet conductance and the area of the TRP were higher in bats that use more exposed roosts than in those bats who use roosts that can buffer environmental conditions. Our results suggest that energy expenditure is similar for all species, but in bats that live in more exposed roosts, the contribution of physiological responses was more important than behavior at the entire range of environmental temperatures, whereas bats in more protected roosts seem to rely more on behavioral responses to thermoregulate. Considering that roosts represent valuable resources, the availability of roosts with the proper microclimatic conditions could determine the patterns of distribution of bat populations.

Far from home: Bat activity and diversity in row crop agriculture decreases with distance to potential roost habitat

As demand for food increases, agricultural production is poised to increase dramatically. Pesticides are commonly used to maintain high crop yield, though they have several drawbacks, including reduced efficacy over time and harmful effects to human and ecosystem health. Bats are highly effective predators of crop pests and have great potential to reduce crop damage resulting from insects. However, few studies have investigated how pest control by bats might change over large expanses of continuous row crop agriculture, which is common in the midwestern USA. Agricultural landscapes offer few roosting opportunities and could be difficult for bats to traverse, which might affect the degree of ecosystem services provided by bats. We hypothesized that with increasing distance into uninterrupted row crop agriculture 1) bat activity would decrease and 2) bat species richness would decrease, but that these effects would be buffered when insect pest abundance is high. We deployed 50 acoustic bat detectors over 10 transects in east-central Illinois from July to September 2021. In each transect, we placed detectors on crop field edges at increasing distance from a large riparian corridor assumed to be frequented by bats. Bat activity was high across the landscape but declined by 56% from the forest edge to 4000 m into row crop agriculture, while bat diversity decreased by 34%. Pest abundance seemed to decrease overall bat activity but had no effect on bat diversity. These results indicate that bats, although able to have a large effect on crop pest reduction, might not be as efficient in suppressing crop pests in vast uninterrupted agricultural landscapes which offer scant roost availability. Our work will inform recommendations to landowners and private lands managers on ways to increase bat access to roosts and forest cover near agricultural areas, thereby enhancing the potential for bats to provide pest control services.

How do we sleep while our beds are burning? Impacts of the 2019–20 mega-fires on a rainforest dependent species – the Golden-tipped Bat Phoniscus papuensis

ABSTRACT The Australian summer of 2019/20 was impacted by megafires of a magnitude and severity never previously recorded. Whilst low severity fire has positive benefits for increased insectivorous bat activity and diversity, little information is available on the impact on rainforest specialised clutter dependant species such as the Golden-tipped Bat Phoniscus papuensis. Our aims were to assess the effects of fire on occupancy of habitat across the geographic range of P. papuensis in NSW, to determine the smaller scale effects of fire on use of diurnal roosts in rainforest through radio tracking and to trial the use of artificial structures to temporarily increase roost availability in burnt habitat. We observed that widespread fire encroaching on rainforest has a negative association with occupancy by P. papuensis, with this metric ~78% lower than in unburnt forest. In burnt areas, P. papuensis preferentially used unburnt refugia for their roosting sites in suspended bird nests and the loss of these habitat structures likely contributes to the disappearance of P. papuensis from the landscape. Artificial roosts were not used in the short-term (< 2 years post fire) and do not appear to be a feasible management tool. With the increasing frequency and extent of wildfires the most important factor for P. papuensis to persist in the landscape into the future is the protection of its habitat through ensuring sensitive management of large tracts of connected rainforest to help buffer against the encroachment of future mega-fires.

Roosting ecology of insectivorous bats in a tropical agricultural landscape

Abstract Bats spend more than half of their life in roosts, where key life events transpire. Therefore the availability and selection of roosts are important to bats everywhere, and may limit their ability to exploit every habitat, including agricultural landscapes such as paddy fields, orchards and tea plantations. This study aimed to investigate the day roosts used by insectivorous bat species in tea plantations of Sri Lanka. We surveyed 18 tea plantations where we recorded a total of 44 roosts involving five families and nine species of bats (Hipposideros galeritus, Hipposideros lankadiva, Hipposideros speoris, Rhinolophus beddomei, Rhinolophus rouxii, Megaderma spasma, Pipistrellus ceylonicus, Pipistrellus coromandra and Miniopterus cf. fuliginosus). Most (26) of the recorded roosts were geomorphic, (11) were anthropogenic, and (7) were in vegetation. H. lankadiva and M. cf. fuliginosus are the only species known to roost exclusively in geomorphic roosts; all others were opportunistic. Although protecting bat roosts is crucial for their conservation, it is challenging in view of existing tea management practices. Therefore, natural roosts should be maintained and protected. The introduction of artificial roosts might increase the number of bats able to forage over tea plantations and maximize their consumption of agricultural pests, thereby increasing tea production.

Are Echo-Reflective Cues Effective to Attract Bats to Newly Placed Artificial Roosts?

The availability of suitable roosts is an important factor affecting the viability of bat populations. In Europe and North-America, the installation of artificial roosts is a standard conservation measure to mitigate the loss of tree cavities or crevices at buildings. How quickly artificial roosts, such as bat boxes, are adopted, depends on how easily the bats can find them, and on their suitability for roosting. While there is some information about how the design of bat boxes influences their occupancy, it is unknown to what extent the use of bat boxes depends on their detectability. In this experimental field study, we studied the roost selection behavior of three forest-living bat species. We investigated whether attaching an external echo-reflector to bat boxes influenced the time until the bats discover a box or the total number of discovered boxes, which are proxies for detectability. We also assessed whether this modification improved the occupancy of newly placed boxes, as a proxy for their attractiveness. As a result of a previous study, all studied bat colonies were familiar with the echo-reflector as an indicator for the suitability of bat boxes as a day roost. For each species, we compared between boxes with and without an echo-reflector, the number of boxes discovered, the number of days elapsed until discovery, the number of subsequent visits, and the number of days that each box type was used as day roosts. Myotis bechsteinii and Myotis nattereri discovered, visited and used more unmodified boxes than boxes with echo-reflectors. Plecotus auritus did not show differences in behavior with regard to the box types. Our results show that attaching an echo-reflector to newly placed artificial roosts does not improve their discovery and subsequent occupation, even when bats are already familiar with this cue as an indicator of suitability. We discuss the implication of our findings for bat conservation.

Diurnal roost selection of northern long-eared bats on the southern edge of their range

Mortality from white-nose syndrome has made management and recovery of the northern long-eared bat (Myotis septentrionalis) a priority. Ensuring availability of diurnal summer roosts, where gestation and rearing of young occurs, is a critical component of successful recovery. However, observed variation in roost selection across the species’ range makes extrapolating data across physiographic regions and habitat types difficult, and limited information exists on roost selection at the southern range extent of the species. Therefore, we examined M. septentrionalis diurnal roost selection toward the southern range extent in northern Georgia, USA. We identified characteristics of desirable roosts for all individuals and for reproductive females by comparing roosts to surrounding vegetation and topographic characteristics at the plot, home range (67 ha), and landscape (17.2 km2) scales. From May to July 2014–2017, we radio tagged 12 female and 4 male M. septentrionalis and located 37 roosts. Bats roosted in cavities, loose bark, and hollow boles of 16 tree species. Over half of roosts (53%) were located below the canopy and in trees with larger diameters than surrounding trees. Bats disproportionately roosted in snags, with relative probability of selecting a snag roost increasing with snag density at the plot scale. On low gradient slopes, roosts occurred more frequently on west-facing aspects but as slope increased bats showed no aspect preference. Results indicate individuals in our study area are indifferent to or actively avoid roosts with high solar exposure. Our results support previous research that management efforts should focus on creating and retaining snags across the landscape and highlight the need for management to consider regional variation in habitat use.

The common noctule bat (Nyctalus noctula): population trends from artificial roosts and the effect of biotic and abiotic parameters on the probability of occupation

AbstractAs urbanization and intense forestry management are increasing, natural bat roosting opportunities, e.g. tree cavities, are constantly declining. A common management practice, especially in urban environments, is the installation of bat boxes. We assessed (1) abundance trends inside artificial bat boxes of the noctule bat (Nyctalus noctula) over 11 years in Neu-Ulm, Germany, and identified (2) parameters affecting the occupation rate. Further, we compared (3) abundance of noctule bats in bat boxes between areas with large availability of natural roosts (forests) and urban areas with primarily artificial roosting structures (parks). Our results revealed a severe decline of noctule bats over 11 years. Further, our results indicate that bat boxes cannot fully replace natural tree cavities. Nonetheless, they support roost availability in areas already altered and providing only low amounts of natural bat roosts. The findings of our study have important implications for the conservation of bats in urbanized landscapes and underline the importance of old and intact forests for local biodiversity.

Northern long-eared bats roosting in a managed forest in south-central Indiana

Forest management can have mixed impacts on tree-roosting bats. Several bat species have benefitted from increased roost availability generated by certain silvicultural methods. To further investigate the impacts of forest management on bats, we conducted a study on the federally threatened northern long-eared bat (Myotis septentrionalis) in managed forests within south-central Indiana, USA. During the summers of 2012–2015, we captured and tracked 69 female bats back to 175 roosts, for which we collected roost-scale data. We compared the frequency that roosts and random points were located in (or within 10 m of) timber harvest openings and first-stage shelterwood cuts as well as their distances to these harvest types. Female northern long-eared bats roosted in a variety of roost types in a variety of tree species. However, bats tended to roost more frequently in crevices and cavities located on live sassafras (Sassafras albidum; which were often hollow) that dominated the forest mid-story and large oaks and maples in the overstory (Quercus spp., Acer spp.). While bats used roosts that were closer to harvest openings and first-stage shelterwood cuts, they did not preferentially use or avoid roosts within these sites based on their availability. However, bats did roost within both harvest openings and shelterwood cuts. Roosts used by bats in this study area are similar to those used in other landscapes, suggesting that forest management does not affect bats’ choice of roost. Our results suggest that the roosting behavior of female northern long-eared bats are not negatively impacted by forest management, at least within these south-central Indiana forests.

Recurring fires in Mediterranean habitats and their impact on bats

The pyrodiversity begets biodiversity hypothesis suggests that wildfires drive habitat diversification, allowing species with different niches to coexist and increasing biodiversity. However, despite numerous wildfires studies, limited research has addressed species-specific effects of fire recurrence. We radio-tracked grey long-eared bats (Plecotus austriacus) from the largest maternity roost (a historical monastery) in an area of the Mediterranean coastal belt with one of the highest fire recurrence rates. Although shrublands cover over 80% of the surroundings and P. austriacus is known to forage in a wide range of habitats, the tracked bats barely used this habitat. They spent 92% of their flight time in scattered small Aleppo pine forest fragments, and never visited any habitat patches that burnt more than three times in the last 30 years. We also report some of the longest foraging and commuting distances (9.95 and 10.5 km) from the roost described for the species in the literature. These results showcase how P. austriacus essentially forage in small forest fragments avoiding recurrently burnt areas, and highlight the colonies’ dependence on the monastery, probably due to limited alternative roost availability. This knowledge needs to be built on and accounted for in biodiversity conservation policies to ensure that species-specific responses to recurring fires in the Mediterranean are addressed.

Roost selection by Mauritian tomb bats (Taphozus mauritianus) in Lilongwe city, Malawi - importance of woodland for sustainable urban planning.

Increasing urbanisation has led to a greater use of artificial structures by bats as alternative roost sites. Despite the widespread presence of bats, roost availability may restrict their distribution and abundance in urban environments. There is limited quantitative information on the drivers of bat roost selection and roosting preferences, particularly in African bats. We explore the factors influencing roost selection in the Mauritian tomb bat (Taphozous mauritianus), within an urban landscape in Lilongwe city, Malawi. Eight building and five landscape features of roosts were compared with both adjacent and random control buildings throughout the city. Bat occupied buildings were situated closer to woodland (mean 709m) compared to random buildings (mean 1847m) but did not differ in any other landscape features explored. Roosts were situated on buildings with larger areas and taller walls, suggesting bats select features for predator-avoidance and acoustic perception when leaving the roost. Bats preferred buildings with exposed roof beams which may provide refuge from disturbance. Whilst roosts are situated more often on brick walls, this feature was also associated with landscape features, therefore its importance in roost selection is less clear. These results are indicative that T. mauritianus selects roosts at both the building and landscape level. The selectivity of T. mauritianus in relation to its roost sites implies that preferred roosts are a limited resource, and as such, conservation actions should focus on protecting roost sites and the woodland bats rely on.

Seasonal changes and the influence of tree species and ambient temperature on the fission-fusion dynamics of tree-roosting bats

Many species of bats live in dynamic associations in which individuals aggregate or split into smaller or larger groups, moving between roost sites, but factors influencing group size and roost switching decisions in bats living in fission-fusion societies are poorly understood. To test the extent to which fission-fusion dynamics are species-specific and shaped by environmental factors, we radio-tracked two closely related species: noctule bats Nyctalus noctula and Leisler’s bats N. leisleri in well-preserved, old-growth stands of the Białowieża Forest, where roost availability and diversity is high and bats can potentially freely exhibit fission-fusion behaviour. We estimated the number of bats per roost and noted the tree species selected as roost sites. We evaluated the influence of ambient temperature and roost tree species on bat group size and the process of roost switching, and their seasonal component. Our results revealed that bat group size showed species-specific differences in seasonal variation, relationship to ambient temperature and tree species. The number of noctule bats emerging from a roost was relatively stable with a weak tendency to decrease during the breeding season while the number of Leisler’s bats emerging from a roost increased when the juveniles started to be volant. Group size of noctule bats increased with ambient temperature. Leisler’s bats formed smaller colonies in oaks and ashes than in other tree species. Roost switching rate was associated with ambient temperature and tree species selected by the bats. The bats changed roosts more frequently when the minimum ambient temperature increased, and less often in ashes than in oaks and other tree species. Our results show that bat group size and roost switching behaviour are shaped by both environmental factors and the stage of reproduction.Significance statementEnvironmental factors may affect group size and roost switching behaviour of bats forming fission-fusion associations, but this is expected to vary depending on body size, environmental conditions, as well as seasonally. Few studies have explored this behaviour in tree-dwelling bats and examined how it differs between species. Here, we studied the group size dynamics and the process of roost switching in closely related bat species living in well-preserved, European old-growth forests, for which the knowledge of these patterns is particularly poor. We demonstrate for the first time that bat group size and roost switching rate relates to roost tree species selected by bats, the ambient temperature and varies seasonally, and that these effects are species-specific. The results point out the importance of the availability of suitable roost trees providing a range of microclimatic conditions for maintaining efficient fission-fusion dynamics throughout the reproductive period.

Flexible foraging strategies in Pipistrellus pygmaeus in response to abundant but ephemeral prey.

There is growing recognition that with sympathetic management, plantation forests may contain more biodiversity than previously thought. However, the extent to which they may support bat populations is contentious. Many studies have demonstrated active avoidance of coniferous plantations and attributed this to the lack of available roost sites and low invertebrate density. In contrast, other work, carried out in plantation dominated landscapes have shown that certain bat species are able to exploit these areas. However, the extent to which bats use plantations for roosting and foraging, or simply move through the plantation matrix to access more favourable sites is unclear. We radio tracked female Pipistrellus pygmaeus over two summers to establish the extent to which individual bats use Sitka Spruce plantations in southern Scotland for foraging and roosting and assess the implications for felling operations on bats. Maternity roosts identified (n = 17) were in all in buildings and most were large (> 500 individuals). We found no evidence of bats roosting in mature Sitka Spruce crop trees, although several bats used roosts in old or dead beech and oak trees as an alternative to their main maternity roost. Home ranges were much larger (mean 9.6 ± 3.12 km2) than those reported from other studies (0.6–1.6 km2), and it is likely that roost availability rather than food abundance constrains P. pygmaeus use of Sitka Spruce plantations. At the landscape scale, most individuals selected coniferous habitats over other habitat types, covering large distances to access plantation areas, whilst at a local scale bats used forest tracks to access water, felled stands or patches of broadleaf cover within the plantation. Sitka Spruce plantations support a high abundance of Culicoides impuctatus, the Highland midge which may act as a reliable and plentiful food source for females during lactation, an energetically expensive period. The use of felled stands for foraging by bats has implications for forest management as wind turbines, following small-scale felling operations, are increasingly being installed in plantations; wind turbines have been associated with high bat mortality in some countries. Decisions about siting wind turbines in upland plantations should consider the likelihood of increased bat activity post felling.

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.

Habitat fragmentation and the prevalence of parasites (Diptera, Streblidae) on three Phyllostomid bat species

AbstractEctoparasitism in bats seems to be influenced strongly by the type of roost preferred by the hosts, and group size; however, the effect of habitat loss and fragmentation on the prevalence of ectoparasites in bats has scarcely been studied. In northeastern Yucatan, Mexico, we estimated the prevalence of infestation by Streblidae flies in three phyllostomid bat species with different roost preferences (caves, trees, or both) in two types of landscape matrices (tropical semi‐deciduous forest and man‐made pastures) that differed in area of forest cover and the number of forest fragments. Habitat fragmentation and the presence of a contrasting matrix may limit the availability of roosts (trees) and the movement of bats across the landscape. Accordingly, we hypothesized higher prevalence of Streblidae infestation in the pasture matrix and in the group of bats that roost in trees. Bat abundance was higher in the pasture matrix; however, the prevalence of infestation was significantly higher in the continuous forest matrix and in bats that roosted in caves. The prevalence of some species of Streblidae was affected by habitat fragmentation in species that roost in caves, such as Desmodus rotundus, as well as those using foliage and caves, such as Artibeus jamaicensis. Our results provide evidence that some species of Streblidae may respond differently to habitat fragmentation than their hosts, generating changes to bat‐ectoparasite interactions in fragmented areas. Environmental variations involving roosts, not evaluated in this study, may influence our results, since these factors affect ectoparasite abundance and reproduction.

Differences between caves with and without bats in a Brazilian karst habitat

ABSTRACT. Since bats shelter in roosts during their period of diurnal inactivity, the quality and availability of roosts are important aspects of their ecology. Karst areas have great potential for the availability of day roosts, since they form caves, which serve as bat shelters. Here we characterize the caves used by bats in a preserved karst area of Southeastern Brazil. Using logistic regression analysis we identified the cave characteristics that influence bat occupation. Sixty-six caves were characterized based on measurements of internal height and width, height and width of the entrance(s) of the cave, number of entrances, maximum horizontal development of cave, and internal temperature and humidity. In nineteen months we found 14 species in 32 caves. Most species were eventually recorded in multiple caves, with the exception of D. rotundus, G. soricina and A. planirostris, which were always found in the same caves. Desmodus rotundus showed maternity roost fidelity. We found no differences in microclimate between the caves that are occupied and those that are not. In other words, the microclimate of the caves studied herein can be characterized as stable over the years. The only predictor affecting the presence of bats in the study area was the cave’s maximum horizontal development: the caves that are occupied have greater horizontal development. Based on our results, we conclude that bats occupy many of the caves and that some species are more frequent in certain caves than in others, including some roosts that are used as maternity roosts. These findings indicate that these caves are important resources for the bats in the karst environment studied, and should be preserved.