Natural Roosts Research Articles

Female little brown bats require both building and natural roosts in a mountainous environment with short summers

AbstractThe little brown bat (Myotis lucifugus) is an endangered species that occurs throughout most of North America. The recovery strategy for little brown bats in Canada identifies a need to understand habitat use and protect important bat habitat across the species' Canadian range; however, bat roosting habitat requirements have not been well studied in mountainous environments within the northern part of the species' range. Our objective was to understand the use of building and natural roosts by female little brown bats in the Canadian Rocky Mountains. Over two summers, we captured little brown bats in Banff, Yoho, and Kootenay National Parks, in Alberta and British Columbia, Canada, and tracked 49 females to their day roosts. Buildings were the only roost type used by radio‐tagged bats of all reproductive stages, the dominant roost type used throughout the reproductive period, and the only structures in which we located maternity colonies. Buildings also appeared to shape the distribution of foraging female and reproductive female bats such that few were captured at long distances from towns and building clusters. Compared with bats in more southern and in non‐mountainous areas, bats in our study area had delayed juvenile weaning and volancy, began hibernation early, and had low reproductive rates. We suggest that buildings are a key habitat for female little brown bats to persist at their current levels in our study area, by providing thermal conditions that promote overwinter survival; additional reproductive delays caused by torpor use in cool natural roosts would likely reduce juvenile and adult female overwinter survival below the levels required to sustain populations. Nevertheless, building colonies were unusually small, and bats had relatively low fidelity to particular building roosts, suggesting that building roosts may not consistently meet bats' needs. Some nonreproductive and pregnant females also frequently used natural roosts, particularly after colder nights; these roosts may be important in facilitating torpor and energy conservation for these bats. Because bats are long‐lived with low reproductive output and low juvenile survival, addressing the needs of both reproductive and nonreproductive individuals is important for population persistence.

Improving the science and practice of using artificial roosts for bats.

Worldwide, artificial bat roosts (e.g., bat boxes, bark mimics, bat condos) are routinely deployed for conservation, mitigation, and community engagement. However, scant attention has been paid to developing best practices for the use of artificial roosts as conservation tools. Although bats readily occupy artificial roosts, occupancy and abundance data are misleading indicators of habitat quality. Lacking information on bat behavior, health, and fitness in artificial roosts, their conservation efficacy cannot be adequately validated. We considered the proximal and ultimate factors, such as evolutionarily reliable cues, that may prompt bats to preferentially use and show fidelity to suboptimal artificial roosts even when high-quality alternatives are available. Possible negative health and fitness consequences for artificial roost inhabitants include exposure to unstable and extreme microclimates in poorly designed roosts, and vulnerability to larger numbers of ectoparasites in longer lasting artificial roosts that house larger bat colonies than in natural roosts. Bats using artificial roosts may have lower survival rates if predators have easy access to roosts placed in conspicuous locations. Bats may be lured into occupying low-quality habitats if attractive artificial roosts are deployed on polluted urban and agricultural landscapes. To advance the science behind artificial bat roosts, we present testable research hypotheses and suggestions to improve the quality of artificial roosts for bats and decrease risks to occupants. Because continued loss of natural roosts may increase reliance on alternatives, such as artificial roosts, it is imperative that this conservation practice be improved.

Factors affecting bat occupancy of boxes in managed coniferous forests

The gradual conversion of forest stands to single-aged and single-species stands is resulting in the loss of natural roosts for many animal groups. The installation of bat boxes is one solution to compensate for the lack of natural roosting opportunities. The box models differ in their design and material, which to some extent can determine their suitability for bats. We investigated the occupancy of 187 boxes made of wood, ceramic and two sizes concrete with styrofoam; and the intra-seasonal (spring migration, breeding, mating/migration) thermal profile for each type of box. The environment of the boxes was defined by parameters that could directly affect the box’s thermal conditions (solar energy availability), or be related to sociality (distances, obstacles) or food availability (edge of forest, water). The box occupancy depended on the box type and the season: styrofoam-concrete boxes were preferred, with a higher occupancy during the mating and migration period (>75%), whereas the highest species richness occurred in ceramic boxes. Box types also differed significantly in their diurnal thermal profiles: the wooden boxes had inside temperatures similar to outside the box, whereas the styrofoam-concrete and with expanded clay aggregate (ceramic type) averaged 2°C higher. Overall, we found 6 bat species, although we concentrated our analysis on the most common species: Pipistrellus nathusii (88%). For this species, none of the parameters that could affect the box thermal condition had an impact on the occupancy, whereas the presence of obstacles and the distance to a water body, proved to be important. To ascertain that our results may be valid and be the result of differences in the box thermal properties, we tested the relationship of the box occupancy to the latitude, using data available in the literature. The occupancy of wooden boxes from the latter dataset significantly decreases with latitude, whereas for the concrete (with addition of sawdust or styrofoam) it increases, although this relationship is not significant and requires a larger sample.

Microhabitat of Myotis leibii summer roosts at the southwestern periphery of their range

Understanding microhabitat use is needed to make sound conservation decisions for at-risk, patchy-habitat specialists, such as rock-habitat specialists. Rock habitats offer unique microclimatic refugia for reptiles and mammals. Eastern small-footed bats ( Myotis leibii (Audubon and Bachman, 1842)) use rock roosts during the summer, but data on these summer roosts are lacking for this species classified as (critically) imperiled in several US states and Canadian provinces and globally endangered. Our goal was to characterize the structure and microclimate of Myotis leibii roosts at the southwestern periphery of their range. We predicted that Myotis leibii roost temperatures would be warmer and less variable than ambient temperatures and that solitary bats would use horizontal roosts cooler at night, whereas maternity group roosts would be vertical and warmer at night. During summers of 2019 and 2020, we recorded physical (e.g., width) and temperature attributes of 58 Myotis leibii roosts at 16 sites in the Ouachita Mountains. Crevice roosts of Myotis leibii had narrow dimensions like elsewhere in their range and roost temperatures (measured with iButtons) were warmer and more variable than ambient temperatures. Group roosts were larger and had more stable temperatures than solitary roosts. These findings may be useful for assessing population threats, monitoring roost suitability, identifying roost-rich areas that need protection, and even planning artificial roost structures where natural roosts are limited.

Home is where the heat is: Thermoregulation of European bats inhabiting artificial roosts and the threat of heat waves

Abstract Anthropogenic land use changes, such as deforestation and commercial forestry, have substantially reduced natural roost sites for European bats. A common conservation solution is to provide artificial roosts (i.e. bat boxes), but there are concerns that these can become hotter than natural roosts in summer and could be death traps during heat waves. Nevertheless, females of several bat species form maternity colonies in these boxes, thus occupying hotter and more humid microclimates than solitarily roosting males. We tested if cooling efficiency and heat tolerance differ between sexes in European bats, and estimated the evaporative water requirements for bats living in bat boxes during hot summer days. We used indirect calorimetry and thermometry to quantify thermoregulation at high air temperatures (Ta) in four species of verspitilionid bats that regularly occupy artificial roosts. We measured resting metabolic heat production, evaporative water loss rates (EWL) and body temperature (Tb) at Ta between 28°C and 48°C during summer. We predicted that females have higher evaporative cooling efficiency (evaporative heat loss/metabolic heat production) than males, allowing them to reach their heat tolerance limit at higher Ta. We found no sex differences in maximum evaporative cooling efficiency, maximum Tb, and maximum Ta tolerated. However, the patterns of increasing EWL with Ta differed between sexes. Females tolerated higher Ta before increasing EWL than males and then rapidly increased EWL to higher values than males at the maximum Ta tolerated. These sex differences in heat dissipation strategies may reflect varying ecological and physiological constraints associated with different summer roosting habits. Synthesis and applications. Our study revealed that some small European bat species are already at risk of succumbing to lethal dehydration during present‐day heat waves, with daytime evaporative water requirements equivalent to ~30% of body mass in sun‐exposed boxes. For conservation managers working with common European bat species, particularly those in monoculture forests with woodcrete bat‐boxes, our physiologically informed recommendations include positioning boxes in diverse locations varying in aspect and sun exposure. This will ensure thermal heterogeneity of roost sites and provide a wide gradient of microclimate conditions, allowing for roost switching when necessary.

Microbial isolates with Anti-Pseudogymnoascus destructans activities from Western Canadian bat wings

Pseudogymnoascus destructans (Pd) is the causative agent of white-nose syndrome, which has resulted in the death of millions of bats in North America (NA) since 2006. Based on mortalities in eastern NA, the westward spread of infections likely poses a significant threat to western NA bats. To help prevent/reduce Pd infections in bats in western NA, we isolated bacteria from the wings of wild bats and screened for inhibitory activity against Pd. In total, we obtained 1,362 bacterial isolates from 265 wild bats of 13 species in western Canada. Among the 1,362 isolates, 96 showed inhibitory activity against Pd based on a coculture assay. The inhibitory activities varied widely among these isolates, ranging from slowing fungal growth to complete inhibition. Interestingly, host bats containing isolates with anti-Pd activities were widely distributed, with no apparent geographic or species-specific pattern. However, characteristics of roosting sites and host demography showed significant associations with the isolation of anti-Pd bacteria. Specifically, anthropogenic roosts and swabs from young males had higher frequencies of anti-Pd bacteria than those from natural roosts and those from other sex and age-groups, respectively. These anti-Pd bacteria could be potentially used to help mitigate the impact of WNS. Field trials using these as well as additional microbes from future screenings are needed in order to determine their effectiveness for the prevention and treatment against WNS.

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.

Avoiding a conservation pitfall: Considering the risks of unsuitably hot bat boxes: Adding context to Crawford & O'Keefe

AbstractAs practitioners of mitigation and conservation of bats, we think use of artificial bat roosts contribute to bat conservation and should be encouraged. Problems with boxes identified by Reed and O'Keefe also exist with natural roosts, and they are more readily studied and managed with artificial than natural roosts. Use of boxes also provides an opportunity for citizen science, but more importantly engenders citizen conservation.

Mixed-species groups in bats: non-random roost associations and roost selection in neotropical understory bats

BackgroundMixed-species groups in animals have been shown to confer antipredator, foraging and other benefits to their members that may provide selective advantages. In most cases, however, it is unclear whether functional benefits are a principal driver of heterospecific groups, or whether groups simply result from simultaneous exploitation of common resources. Mixed-species groups that form independently of environmental conditions may, however, evidence direct benefits of species associations. Bats are among the most gregarious mammals, with sometimes thousands of individuals of various species roosting communally. Despite numerous potential functional benefits of such mixed-species roosting groups, interspecific attraction has never been shown. To explore alternative explanations for mixed-species roosting, we studied roost selection in a speciose neotropical understory bat community in lowland rainforest in Costa Rica. Long term roost data were recorded over 10 years in a total of 133 roosts comprising both natural roosts and structurally uniform artificial roosts. We modelled bat roost occupancy and abundance in each roost type and in forest and pasture habitats to quantify the effects of roost- and environmental variability.ResultsWe found that bat species presence in natural roosts is predictable from habitat and structural roost parameters, but that the presence and abundance of other bat species further modifies roost choice. One third of the 12 study species were found to actively associate with selected other bat species in roosts (e.g. Glossophaga commissarisi with Carollia sowelli). Other species did not engage in communal roosting, which in some cases indicates a role for negative interspecific interactions, such as roost competition.ConclusionsMixed-species roosting may provide thermoregulatory benefits, reduce intraspecific competition and promote interspecific information transfer, and hence some heterospecific associations may be selected for in bats. Overall, our study contributes to an improved understanding of the array of factors that shape diverse tropical bat communities and drive the dynamics of heterospecific grouping in mammals more generally.

Natural roosts used by bats in Central Amazonia, Brazil

Natural roosts used by bats in Central Amazonia, Brazil

Widespread use of artificial habitats by shorebirds in Australia

ABSTRACT Shorebirds in the East Asian-Australasian Flyway have experienced population declines linked to loss of coastal wetlands. Despite this vulnerability to habitat loss, shorebirds regularly use artificial habitats, especially for high-tide roosting. Understanding the distribution of shorebirds in artificial versus natural roosts could inform habitat management strategies aimed at population recovery. We analysed time-series of high-tide shorebird monitoring data from five developed regions of Australia where artificial habitat use has previously been documented and made three key discoveries. First, artificial habitat use was generally high across the regions, with >50% of the average proportion of the regional population of 39 of 75 species-region combinations (52%) using artificial habitats at high tide. Second, in 84% of species-region combinations the average proportion of birds that used artificial habitats from the time of their establishment onward did not show a significant temporal trend. Third, migratory and coastal specialist species showed lower proportional artificial habitat use than non-migratory and generalist/inland specialist species. These findings showing consistent, widespread use of artificial habitats by large shorebird aggregations at high tide suggest that a framework for high-tide habitat management that includes artificial habitats alongside preservation of remaining natural habitats could make a significant contribution to shorebird conservation in Australia.

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.

Bat conservation and ecotourism: the case of two abandoned tunnels in Salamanca, Western Iberia

Underground roosts play a key role in the conservation of cave-dwelling bats. In regions where natural roosts are scarce, human-made artificial roosts can host important populations of these species. The roosts studied in the present work are two railway tunnels abandoned in 1984 that have become one of the biggest cavedwelling bats roosts in the region. Several thousands of roosting bats were reported during summer in the 1990s, and more recently, in the mid-2010s, large groups of hibernating bats and maternity colonies were found in them (Lizana-Ciudad 2015, Hernández-Tabernero et al. 2016). Now, as a measure for local economic development, a hiking route following the railroad has been habilitated and it could threaten bat colonies if many visitors enter into the tunnels. In this work, we present the data of monthly monitoring carried out during 2018 and we propose conservation measures that would allow the coexistence of the touristic hiking route and the remarkable colonies of cave-dwelling bats that the tunnels host. This monitoring shows that the occupation of the roosts is very dynamic, with different species occupying each of them in different seasons. Overall, the longest tunnel is mainly a winter hibernaculum, while the shorter one is used as a breeding roost which hosts large colonies of bats. The most abundant species in the studied roosts were Miniopterus schreibersii, Rhinolophus ferrumequinum, Myotis myotis, and Myotis blythii. These roosts seem to be part of a large transnational network of underground roosts that are well known on the Portuguese side with very limited knowledge on the Spanish side. We hope by implementing simple measures, these roosts can be preserved whilst still maintaining the hiking route for visitor enjoyment and promoting the economic development of the area.

Evidence for Communal Roost Size Regulation in Heliconius erato Butterflies (Nymphalidae)

Communal roosting behavior in Heliconius passion-vine butterflies has fascinated scientists for centuries. Despite recent research on the complex dynamics involved with this behavior, little work has been done to examine whether butterflies regulate their communal roost sizes and if there is preference to form roosts of a particular size. Here I present results from two studies, that tested 1) whether wild-captured Heliconius erato butterflies, exposed to different roost sizes in captivity, prefer to join small, medium, or large-sized roosts; and 2) whether established H. erato butterflies in natural wild populations abandon roosts when they become too large. In captivity, butterflies significantly preferred to join small- and medium-sized aggregations, and avoided large aggregations, when introduced to a new environment. In the wild, butterfly attendance decreased significantly as roost size increased, showing that butterflies leave natural roosts when they become too large or crowded. Although a number of potential explanations exist for the adaptive significance of communal roost size regulation in H. erato, one of the most striking details about these results are that preferred roost size by individual butterflies corresponds with the average number of butterflies found in natural roosts. This preferred roost size also overlaps with previous studies showing an experimentally optimal roost size with the same number of butterflies (for anti-predatory benefits), in this species in this same field location. These results combine multiple sources of evidence from old and new data suggesting that optimal communal roost sizes exist in Heliconius and that the butterflies regulate their roost sizes in their home ranges. Further studies are welcome to help understand the decision-making process used by these butterflies for joining – or abandoning – communal roosts.

External temperature and distance from nearest entrance influence microclimates of cave and culvert-roosting tri-colored bats (Perimyotis subflavus).

Many North American bat species hibernate in both natural and artificial roosts. Although hibernacula can have high internal climate stability, they still retain spatial variability in their thermal regimes, resulting in various “microclimates” throughout the roost that differ in their characteristics (e.g., temperature and air moisture). These microclimate components can be influenced by factors such as the number of entrances, the depth of the roost, and distance to the nearest entrance of the roost. Tri‐colored bats are commonly found roosting in caves in winter, but they can also be found roosting in large numbers in culverts, providing the unique opportunity to investigate factors influencing microclimates of bats in both natural and artificial roost sites. As tri‐colored bats are currently under consideration for federal listing, information of this type could be useful in aiding in the conservation and management of this species through a better understanding of what factors affect the microclimate near roosting bats. We collected data on microclimate temperature and microclimate actual water vapor pressure (AWVP) from a total of 760 overwintering tri‐colored bats at 18 caves and 44 culverts. Using linear mixed models analysis, we found that variation in bat microclimate temperatures was best explained by external temperature and distance from nearest entrance in both caves and culverts. External temperature had a greater influence on microclimate temperatures in culverts than caves. We found that variation in microclimate AWVP was best explained by external temperature, distance from nearest entrance, and proportion from entrance (proportion of the total length of the roost from the nearest entrance) in culvert‐roosting bats. Variation in microclimate AWVP was best explained by external temperature and proportion from entrance in cave‐roosting bats. Our results suggest that bat microclimate temperature and AWVP are influenced by similar factors in both artificial and natural roosts, although the relative contribution of these factors differs between roost types.

Activity of Aerial Insectivorous Bats in Two Rice Fields in the Northwestern Llanos of Venezuela

Even though agricultural lands provide abundant food to aerial insectivorous bats (AIB), our understanding of how spatio-temporal factors affect their foraging behavior in these habitats is limited and mostly restricted to temperate regions. In this study, we examined species richness, composition and patterns of activity of AIB in rice fields in the northwestern Llanos of Venezuela. Between 2013 and 2014, we conducted acoustic monitoring of AIB in two rice fields with contrasting forest cover, throughout three phases of the life cycle of this crop (vegetative, reproductive, and ripening), during the dry and rainy season. Out of 108 h recorded, we processed 12,630 files and identified 15 species and 10 sonotypes of AIB from families Molossidae, Mormoopidae, Vespertilionidae, Emballonuridae and Noctilionidae. Molossus molossus and Myotis nigricans showed the highest levels of feeding and general activity across species. The index of general activity (IGA) of AIB was higher above rice fields with more surrounding forest cover, during the dry season and throughout the entire life cycle of the plant. Relative feeding activity (RFA) did not change with respect to forest cover, season or crop phase, but a significant effect of the interaction of these factors was observed on this variable. The response of IGA and RFA to forest cover, season or crop phase was different between M. molossus and M. nigricans and among functional groups. Our results indicate that rice fields in the Venezuelan Llanos can be active feeding grounds for open space and edge-habitat foraging species of insect-feeding bats. Forest patches can promote AIB activity by favoring foraging of ‘edge’ species above rice fields. Higher general activity of most AIB species during the dry season suggests that rice fields are used more intensively when insect populations decrease in semi-deciduous forest patches around them. Overall, our results suggest that availability of abundant feeding areas to AIB, provided by the rice fields, together with presence of artificial and natural roosts to these bats, could ensure year-round permanence of a rich ensemble of AIB in the rice field-forest landscape in the northwestern Llanos of Venezuela. Some of these species could be the subject of field experiments to test their value in the control of rice's insect pest populations.

Does bat response to traffic noise support the misleading cue hypothesis?

AbstractThe world has become a noisier place due to the increase in urbanization. Noise is generally considered an impediment, altering an animal’s behavior through masking or distraction. But noise can also provide useful information about the environment. For animals that rely on natural environmental noise as an indicator of favorable foraging conditions, increasing levels of anthropogenic noise might mislead informed decision-making. Bats use rain noise, a natural environmental cue, to delay their emergence from the roost, presumably to avoid sensory and metabolic costs associated with foraging in heavy rain. Here we tested the “misleading cue hypothesis,” asking whether traffic noise is mistaken for rain noise by bats. Given the acoustic similarity between rain noise and traffic noise, we predicted that bats would confuse the two. We conducted a playback experiment using rain, traffic, and ambient noise at natural roosts of common big-eared bats (Micronycteris microtis, Phyllostomidae) and recorded bat emergence behavior. In contrast to their response to rain noise, the bats did not delay roost emergence in response to traffic noise. Thus, we found that bats were able to discriminate between traffic noise and rain noise and were not misled by similarity in acoustic parameters in the two noise types, when emerging from their roost. Emerging bats did show more exploration flights during traffic noise than during rain noise, but not during ambient noise, suggesting that they perceive traffic noise as a novel acoustic cue. Our data provide new insights into perception of traffic noise by bats.

Noise as an informational cue for decision-making: the sound of rain delays bat emergence.

Background noise can have strong negative consequences for animals, reducing individual fitness by masking communication signals, impeding prey detection and increasing predation risk. While the negative impacts of noise across taxa have been well documented, the use of noise as an informational cue, providing animals with reliable information on environmental conditions, has been less well studied. In the tropical rainforest, downpours can be intense and frequent. Strong rainfall may impede efficient orientation and foraging for bats that need echolocation to both navigate and detect prey, and can result in higher flight costs due to increased metabolic rates. Using playback experiments at natural roosts, we tested whether two bat species, differing in their hunting strategies and foraging habitats, use rain noise as a cue to delay emergence from their roosts. We found that both species significantly delayed their emergence time during rain noise playbacks versus silence and ambient noise controls. We conclude that bats can use background noise, here the acoustic component of rainfall, as a reliable informational cue to make informed decisions, in this case about whether to initiate foraging trips or remain in the shelter of their roosts. Our findings suggest that environmental background noise can sometimes be beneficial to animals, in particular in situations where other sensory cues may be absent.

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.

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.