Roost Trees Research Articles

Summer roost site selection of a declining bat species

AbstractSummer habitats are critical to bat population persistence as they support multiple life history stages, including maternity colonies, nursery sites, and foraging locations. The tricolored bat (Perimyotis subflavus) is a hibernating North American bat species that uses forested landscapes during summer months; however, information on the summer habitat requirements is limited. The objective of this work was to quantify the characteristics of roost sites selected by tricolored bats during summer months. We captured, tagged, and tracked 15 bats using radio-telemetry to 55 roost locations. At each roost, we recorded roost habitat characteristics and other forest characteristics within a 0.1 ha circular plot surrounding the roost tree and a 1 km buffer at the landscape scale. We repeated these measurements for three random trees per roost tree to characterize available habitat for selection. We used a suite of mixed conditional logistic regression models to test multiple factors known to influence roost-site selection for various bat species and compared using Akaike information criterion to select the best model. The top model at the roost scale demonstrated that roost selection was influenced by roost tree height, while the landscape scale was influenced by deciduous forest and distance to roads. There is a critical information gap for the ongoing recovery of tricolored bats; better understanding of summer habitat and proper forest management implications, as well as information on scale-specific habitat selection, is needed to better understand tricolored bat management needs.

Roost characteristics and fidelity of silver‐haired bat maternity colonies in a floodplain cottonwood forest

AbstractThe maternal roosting behavior of migratory, tree‐dwelling bat species remains poorly understood. From 2016 to 2020 we radio‐tagged 53 adult female silver‐haired bats (Lasionycteris noctivagans) and tracked them to their day roosts to evaluate roosting habits in a cottonwood (Populus) forest in the floodplain of the Bitterroot River in western Montana. We investigated roost tree characteristics of maternity colonies such as canopy closure, tree size, and decay stage, as well as the daily roost fidelity of tagged bats. Additionally, we marked 55 bats with passive integrated transponder (PIT) tags to assess interannual fidelity to summer habitat. We tracked bats to 94 unique roost trees. Based on previous studies, we expected silver‐haired bat maternity colonies to roost in tall, large diameter trees. We modeled roosting probability as a function of tree height, day of year, and the interaction of these terms. We found bats preferred taller trees earlier in the year, but overall roosting probability decreased throughout the season and tree height had lesser influence on roosting probability later in the year. Bats used tall trees with high canopy closure in early stages of decay during periods of pregnancy and lactation, while the effect of these tree attributes lessened later in the season, perhaps after lactation when energetic constraints were reduced for adult females to prepare for migration by entering torpor during the day. Bats used an average of 5.2 roost trees during the young rearing period and remained in the same roost for an average of 1.5 consecutive days. While daily roost fidelity was low, we documented interannual fidelity to summer habitat from nine individuals. We found silver‐haired bat roosting preferences vary with time, are tree‐specific, and policies targeting conservation of the species should manage flood regimes to promote cottonwood establishment, height growth, and a mosaic of riparian habitats.

A novel method for estimating avian roost sizes using passive acoustic recordings using deep neural network

Abstract Communal bird roosts serve as information centres and a means of thermoregulation for many species. While some communally roosting species are major pests and cause dis‐amenities, others are of conservation concern. Estimating the population of roosting birds can provide a useful proxy of population size and possibly a more reliable estimate than other sampling techniques. However, estimating these populations is challenging as some roosts are large and often occluded in foliage. Previous acoustic methods such as paired sampling, microphone arrays and use of call rate have been used to estimate bird abundances; however, these are less suited for estimating large roost populations where hundreds of individuals are calling in unison. To address this challenge, we explored using machine learning techniques to estimate a roost population of the Javan myna, Acridotheres javanicus, an invasive species in Singapore. While one may expect to use sound intensity to estimate roost sizes, it is affected by various factors such as distance to the recorder, local propagation conditions (e.g. buildings and trees), weather conditions, and noise from other sources. Here, we used a deep neural network to extract higher order statistics from the sound recordings and use those to help estimate roost sizes. Additionally, we validated our method using automated visual analysis with a dual‐camera setup and manual bird counts. Our estimated bird counts over time using our acoustic model matched the automated visual estimates and manual bird counts at a selected Javan myna roost, thus validating our approach. Our acoustic model estimated close to 400 individual mynas roosting in a single tree. Analyses of additional recordings of Javan myna roosts conducted on two separate occasions and at a different roost location using our acoustic model showed that our roost estimates over time also matched our automated visual estimates well. Practical implication: Our novel approach of estimating communal roost sizes can be achieved robustly using a simple portable acoustic recording system. Our method has multiple applications such as testing the efficacy of avian roost population control measures (e.g. roost tree pruning) and monitoring the populations of threatened bird species that roost communally.

Distribution and Habitat Selection of Indian Flying Fox, Pteropus medius (Temminck, 1825) in Uttar Pradesh, India

The present study examines the distribution and habitat selection of Indian flying fox, Pteropus medius in Uttar Pradesh, India. A through field work conducted across six districts revealed 22 roosting locations with a total population of approximately 12,023 bats. These sites were located at rural (12), semi-urban (2), urban (1), agricultural (5), and industrial (2) areas, and a majority of roost sites observed close to human habitations. Pteropus medius preferred to roost on 20 species of trees which indicate wide-ranging habitat preferences. Although there were considerable differences in tree attributes across different species, such as tree height (ranging from 9.54 to 26.03 meters), canopy width (varying from 8.59 to 25.09 meters), crown height (ranging from 1.19 to 18.90 meters), circumference (ranging from 0.54 to 3.65 meters), and DBH (ranging from 0.17 to 3.73 meters), and there was no notable variation in bat occupancy per roost tree. The results of the regression analysis emphasized the significance of canopy width as a predictor of colony size, indicating its importance in identifying suitable roosting habitats for P. medius. ANOVA analysis indicated differences in tree characteristics across species, highlighting the necessity for through habitat evaluations. Subsequent post-hoc examination clarified distinct clusters of tree species with significant variations in roosting site features. These results underscore the intricate relationship between tree attributes and bat populations, emphasizing the significance of well-informed conservation approaches for the sustainable preservation of P. medius and the overall ecosystem well-being.

The heat is on: Thermoregulatory and evaporative cooling patterns of desert-dwelling bats

For small endotherms inhabiting desert ecosystems, defending body temperatures (Tb) is challenging as they contend with extremely high ambient temperatures (Ta) and limited standing water. In the arid zone, bats may thermoconform whereby Tb varies with Ta, or may evaporatively cool themselves to maintain Tb < Ta. We used an integrative approach that combined both temperature telemetry and flow through respirometry to investigate the ecological and physiological strategies of lesser long-eared bats (Nyctophilus geoffroyi) in Australia's arid zone. We predicted individuals would exhibit desert-adapted thermoregulatory patterns (i.e., thermoconform to prioritise water conservation), and that females would be more conservative with their water reserves for evaporative cooling compared to males. Temperature telemetry data indicated that free-ranging N. geoffroyi were heterothermic (Tskin = 18.9–44.9 °C) during summer and thermoconformed over a wide range of temperatures, likely to conserve water and energy during the day. Experimentally, at high Tas, females maintained significantly lower Tb and resting metabolic rates, despite lower evaporative water loss (EWL) rates compared to males. Females only increased EWL at experimental Ta = 42.5 °C, significantly higher than males (40.7 °C), and higher than any bat species yet recorded. During the hottest day of this study, our estimates suggest the water required for evaporative cooling ranged from 18.3% (females) and 25.5% (males) of body mass. However, if we extrapolate these results to a recent heatwave these values increase to 36.5% and 47.3%, which are likely beyond lethal limits. It appears this population is under selective pressures to conserve water reserves and that these pressures are more pronounced in females than males. Bats in arid ecosystems are threatened by both current and future heatwaves and we recommend future conservation efforts focus on protecting current roost trees and creating artificial standing water sites near vulnerable populations.

Impact of reproduction on roost selection of the Indian flying fox, Pteropus medius (Temminck, 1825)

A thorough knowledge of ecology and behaviour is a clear requirement for proper conservation and management of a species. The Indian flying fox, Pteropus medius (formerly P. giganteus Brünnich, 1782), lives gregariously in large trees and spends a considerable time at day roosts. The roost sites play vital roles in survival, reproduction and population persistence. This study describes changes in roost selection, colony size and behaviours of P. medius during reproductive and non-reproductive seasons in a large colony at Mohanlal Ganj, Lucknow (India). The colony size was significantly lower during the summer non-reproductive season (486.5 ± 121.1 SD) than during the spring (1942 ± 488.8 SD) and monsoon (2367.7 ± 277 SD) reproductive seasons. The number of roost trees utilised and roost site selection differed across the reproductive and non-reproductive seasons. The bats occupied the southern periphery of the sampled garden during the non-reproductive period (summer), whereas they shifted to the central and northern parts of the garden during the reproductive seasons and winter periods. The reproductively active individuals secluded themselves from the reproductively inactive colony members. The selection of secluded roost sites during the reproductive period demonstrates the need for social exclusion, less disturbance, and reduced mate competition. The higher population size during the reproductive period might be due to the immigration of bats, most probably male individuals, facilitating gene flow from nearby populations and thus increasing genetic diversity and species resilience.

Distribution status and roost characteristics of Indian Flying Fox Pteropus medius Temminck, 1825 (Mammalia: Chiroptera: Pteropodidae) in Kurukshetra district, Haryana, India

The Indian Flying Fox Pteropus medius plays a major role in the maintenance of a healthy ecosystem and is very specific in selecting roosting sites. The present study was conducted from January 2021 to March 2022 to document the occurrence of roosting colonies, the roosting sites and the population characteristics of P. medius in Kurukshetra district, Haryana. Of the 10 roosting sites identified in four tehsils of Kurukshetra district, 60% were located close to water sources, 20% were near agricultural fields, and the remaining sites were in roadside plantations. Eight roosting sites were observed to be permanent and two were temporary. A total of 233 trees belonging to seven families, eight genera, and nine species were identified as roost trees for this species. Our survey results show that P. medius preferred (77.42%) roosting majorly on trees of the Myrtaceae family (Eucalyptus), while very few individuals (0.5%) were recorded on Phoenix dactylifera. A positive Pearson correlation between the population of the roosting bats and the roost tree characteristics such as height (r = 0.320, p &lt;0.001), dbh (r = 0.226, p &lt;0.001), and circumference (r = 0.293, p &lt;0.001) was also observed. The findings of the current study revealed that P. medius prefers to roost on tall trees with large diameters at breast height, located near water bodies and agricultural fields. Protecting such large and tall trees would benefit the conservation of roosting sites of this species and its populations.

Geographies of Coexistence: negotiating urban space with the Grey-Headed Flying-Fox

ABSTRACT The global phenomena of wildlife migration to urban areas unsettle notions of the city being exclusively for humans. Using a dialogue between urban political ecology and multispecies ethnographies we explore entanglement as a way forward for humans and non-humans to work together. Over the last two decades the Grey-Headed Flying-Fox has become increasingly prevalent in the urbanised spaces of south-east Australia, establishing roosts in trees in urban parks, recreational areas and residential yards. Human–flying-fox relations are complex, and tensions between demands for lethal control and recognition of their ecological role and threatened species status forces humans to negotiate urban space for coexistence. Public policy and planning documents are analysed to identify emerging narratives as coexistence is negotiated around human amenity, the withdrawal of what we call the social licence to harm, legislative conservation and flying-fox agency.

Roost characteristics of Indian flying fox along urban noise gradient: A case study in Sallaghari Forest, Kathmandu Valley, Nepal

The Indian flying fox, Pteropus medius is a fruit bat that contributes significantly to seed dispersal and pollination services. These bats face serious threats from the loss of roosting trees due to urbanization and deforestation. This study aimed to assess the roost characteristics of Indian flying foxes and the effects of anthropogenic noise on roost tier selection in an urban forest patch. We carried out population surveys of Indian flying foxes in the Sallaghari Forest in Kathmandu Valley, Nepal by direct roost count method from July to November 2023. Further, we quantified the intensities of anthropogenic noise at every five-meter interval along the transects from the forest edge towards the main forest and recorded the minimum roosting heights at each point. Indian flying foxes were found to be roosting on trees belonging to six species. Eucalyptus sp. was the most abundant roost tree (50%) in the forest whereas the highest relative abundance of roosting Indian flying foxes was on Populus ciliata (40.1%). The regression analysis revealed that tree DBH and height and the combined interaction of height and canopy cover significantly increase the abundance of Indian flying foxes. The noise intensity at ground level and roosting height of Indian flying foxes showed a significant strong positive relationship indicating their roosting at higher tier under intense noise. We recommend measures for reducing anthropogenic noises and conserving large and tall trees to ensure the roosting habitat of Indian flying foxes in urban setups.

Powerful wind kills hundreds of birds

Extreme weather events are predicted to occur with increasing frequency as a result of global climate change. These extremes take multiple forms. This note reports an abnormal weather event in which winds, apparently Force 10 on the Beaufort Scale (90-100 km/hour), killed hundreds of birds at a farmhouse in the Karoo, South Africa. The wind was so strong that it removed birds from their roosts in trees and flung them against the walls of the farmhouse with such force that it killed them. There are no published accounts of comparable events in southern Africa.

Seasonal roost characteristics and fall behavior of coastal populations of Northern Myotis (Myotis septentrionalis)

Abstract Temperate bats exhibit seasonal and sex differences in resource selection and activity patterns that are influenced by ambient conditions. During fall, individuals face energetic trade-offs as they make choices relating to migration, mating, and hibernation that may diverge for populations throughout their range. However, research has largely focused on the summer maternity and winter hibernation seasons, whereas the prehibernation period remains comparatively understudied. Northern Myotis (Myotis septentrionalis) have experienced precipitous population declines from white-nose syndrome (WNS), leading to their protected status in the United States and Canada. Therefore, understanding their ecology throughout the year is paramount to inform conservation. We compared seasonal roosts and documented fall behaviors between study sites and sexes on 3 islands: Long Island (New York), Martha’s Vineyard, and Nantucket Island (Massachusetts). Between 2017 and 2020, we radio-tracked 54 individuals to analyze activity patterns and characterize fall roosts to compare with previously known summer roosts. Summer tree roosts were of smaller diameter, later stages of decay, and lower canopy closure than those used in fall. Both sexes selected trees of similar diameter and decay stage during fall. Anthropogenic roost use was documented in both seasons but use of anthropogenic structures was greater during fall and increased as the season progressed. Bats made short inter-roost movements with males traveling greater distances than females on average. Activity occurred until late November, with males exhibiting a longer active period than females. We tracked 23% of tagged bats to local hibernacula in subterranean anthropogenic structures, the majority of which were crawlspaces underneath houses. Use of anthropogenic structures for roosts and hibernacula may facilitate survival of this species in coastal regions despite the presence of WNS infections. Timing of restrictions on forest management activities for bat conservation may be mismatched based on prehibernation activity observed in these coastal populations, and the conservation of habitat surrounding anthropogenic roosts or hibernacula may be warranted if the structures themselves cannot be protected.

Seasonal roost selection of wild turkeys at their northern range edge

Wild turkeys Meleagris gallopavo are diurnally active birds that spend the dark hours roosting in trees. We tested the hypothesis that multiple benefits exist for roost tree selection by wild turkeys, including thermoregulation, resource acquisition, and protection from predators. We compared 48 roost trees used by eastern wild turkeys M. g. silvestris in Ontario, Canada to 48 non‐roost trees sampled contemporaneously during 2017–2019 to determine roost site selection between seasons. Mean (± SE) roost tree height (21.4 ± 0.8 m) was taller than non‐roost trees (18.2 ± 0.8 m), and roost trees were also larger in diameter at breast height (58.1 ± 5.5 vs 38.7 ± 3.1 cm). Using ibuttons to collect microclimate temperatures at the tree, we found that mean temperature (± SE) of a deciduous roost (14.5 ± 0.1°C) was higher than temperature at either a coniferous roost (13.9 ± 0.1°C) or ambient temperature (13.2 ± 0.1°C) during the summer months. In winter however, we did not find any relationship between temperature and tree type. Roosts were closer to buildings (150.8 ± 26.0 m) in the winter compared to summer and year‐round roosts, and winter roosts were also farther away from crops (395.2 ± 63.7 m) compared to roost sites used year‐round. Summer roosts were closer to roads (143 ± 36.3 m) than the roosts in the winter and roosts used year‐round. Our data suggest that thermoregulation is not the driving force behind roost selection; instead, predator avoidance appears to play the most important role, with some weaker evidence in support of proximity to resources.

Resource selection and home range size variation of Atlantic Forest woodpecker species: Implications for selective logging and conservation

Understanding the habitat requirements of forest-dependent species, such as woodpeckers, is crucial for effective management strategies in environments facing significant anthropogenic pressures. During 2013–2019, we investigated the variation in the availability of forest structural attributes in two unlogged forests, one forest with active selective logging, and one forest 33 years after it had been logged, in the Upper Paraná Atlantic Forest in Misiones, Argentina. Then, we studied the selection of the forest attributes by co-occurring populations of Helmeted Woodpecker (Celeus galeatus), Lineated Woodpecker (Dryocopus lineatus), and Robust Woodpecker (Campephilus robustus), along with their correlation to variations in home range sizes of woodpeckers. We found that the density of potential nest trees of the three woodpecker species, the density of potential Helmeted Woodpecker roost trees, the basal area ha−1 of live trees ≥ 30 cm DBH, the density of live large trees ≥ 30 cm DBH, and the volume of dead wood ≥ 30 cm diameter differed among study sites. Home range sizes of Helmeted Woodpeckers decreased with higher potential roost tree density and greater understory bamboo cover. The home range sizes of Robust Woodpeckers decreased with a higher density of dead trees, while home range sizes of Lineated Woodpeckers were not influenced by any of the variables we measured. The three woodpecker species selected diameter classes and tree species for foraging and nesting disproportionally to their availability. Helmeted Woodpecker preferred guatambú (Balfourodendron riedelianum) over other trees for roosting. We recommend considering key attributes associated with smaller home range sizes of the threatened Helmeted Woodpecker in sustainable forest management, as these attributes are also important for the other two woodpecker species. To ensure the availability of the resources selected by these woodpeckers, we recommend increasing the legal minimum cutting diameter to 60 cm for grapia (Apuleia leiocarpa), guatambú, rabo duro (Lonchocarpus leucanthus) and palo de canga (Symplocos uniflora), and to 50 cm for laurel negro (Nectandra megapotamica) and laurel amarillo (N. lanceolata). We found similar quantities of most of the tree resources we measured in unlogged forests and a forest undergoing a natural recovery for 33 years after the cessation of selective logging, and we recommend that more logged forests be restored in this manner.

Multi-scale assessment of roost selection by 'ōpe'ape'a, the Hawaiian hoary bat (Lasiurus semotus).

The Hawaiian hoary bat (Lasiurus semotus; Chiroptera: Vespertilionidae), commonly and locally known as 'ōpe'ape'a, is a solitary, insectivorous, and foliage-roosting species distributed across a wide range of habitats in lowland and montane environments. The species, as with many others in the Hawaiian archipelago, are facing a suite of challenges due to habitat loss and degradation, introduced predators and pests, and climate change. An understanding of the roost requirements of foliage-roosting tree bats is critical to their conservation as these habitats provide several important benefits to survival and reproduction. Because little is known about 'ōpe'ape'a roost ecology and considerable effort is needed to capture and track bats to roost locations, we examined resource selection at multiple spatial scales-perch location within a roost tree, roost tree, and forest stand. We used a discrete choice modeling approach to investigate day-roost selection and describe attributes of roost trees including those used as maternity roosts. 'Ōpe'ape'a were found roosting in 19 tree species and in an assortment of landcover types including native and non-native habitats. Our results are largely consistent with findings of other studies of foliage-roosting, insectivorous tree bats where bats selected roost locations that may offer protection and thermoregulatory benefits.

Habitat differences and roost selection between two disparate landscapes by a neotropical bat (Artibeus lituratus) in the Atlantic Forest of Paraguay

1. Species that range across heterogeneous environments should optimally modify their behavior to local conditions. We explored this adaptive habitat-use concept by examining a primary resource: bat roosts. If landscape types differ in roosting characteristics, changes in roost use should manifest. 2. We tested this relationship between bats and landscape by contrasting bat roost use between contiguous forest and fragmented matrix. We posited that if forest structure is different and roosts are limited, fragmentation may affect roost use and selection. 3. The neotropical great fruit-eating bat (Artibeus lituratus) is a common bat species in Alto Paraná Atlantic Forests of eastern Paraguay. We collected habitat use data by following 39 telemetered bats, and compared tree and stand characteristics from roost trees and random trees in both contiguous and matrix landscapes. 4. Diameter at breast height (DBH) of trees used as roosts was greater than the DBH of random trees, but only in the contiguous landscape. Tree height and crown cover density decreased in tandem and sequentially: contiguous landscape (roost trees taller with denser crowns than random trees), then matrix landscape (random trees taller with denser crowns than roost trees). 5. Across both landscapes, roost trees had greater vine species richness, and more vine knots and surrounding vines than random trees. Also, the nearest taller tree occurred closer to random trees than roost trees. Furthermore, canopy height around random trees was taller than around roost trees, and random trees tended to have more surrounding basal area than roost trees. 6. When A. lituratus roost selection in the Atlantic Forest is considered across disparate landscapes, a tall, large-boled tree is not the most important predictor. The strongest indicators of an A. lituratus roost were a vine-covered tree, in an uncluttered stand of smaller trees. While roost selection by A. lituratus also differed between contiguous and matrix landscapes, the aforementioned indicators remained consistent. Ergo, behavioral differences between these two A. lituratus groups cannot be explained through roost-use alone. Further exploration of tropical bat roosting is needed if a true comprehensive and holistic synthesis of bat roosting ecology is to be achieved.

When bat eats bat: diet and roosts of the greater broad-nosed bat (Scoteanax rueppellii) across different regions and habitats

Roost selection and diet are fundamentally important to bats and can vary geographically and with habitat. The greater broad-nosed bat (Scoteanax rueppellii) is infrequently captured and poorly known, meaning appropriate conservation actions are difficult to determine. To assess variation across different habitats, we collected faecal samples for dietary analysis and radio-tracked individuals to identify roost trees at four different sites across New South Wales, Australia. Analysis of droppings verified beetles as the main prey in each study area except one dominated by mangroves, and confirmed for the first time carnivory in wild-caught individuals from the presence of hair from other bat species in its droppings. Very large, hollow trees were used as maternity roosts, being typically larger than neighbouring trees. Roosting habitat varied from wet sclerophyll forest in gullies to old-growth mangroves, and tree species used as roosts also varied. Colony size at maternity roosts was often 50–100 bats and fidelity to the maternity roost varied, with some being switched almost daily and others occupied for at least several days. One maternity roost was re-used 2 years later. Both the importance of beetles in the diet and roosts located in more productive landscapes suggest coastal plains and foothills may represent key habitat.

Diurnal tree-roosting by Eastern Horseshoe Bats Rhinolophus megaphyllus

ABSTRACT The Eastern Horseshoe Bat Rhinolophus megaphyllus is known to roost in caves, disused mines, tunnels and old buildings. Other tropical Rhinolophus species are reported to use tree roosts, but this has not been reported for R. megaphyllus. We describe the features of a R. megaphyllus tree roost identified on the mid north coast of NSW. The tree was monitored over a 10-year period before the tree's collapse during the 2019/2020 wildfires. The tree was not observed to be used in the maternity season. The discovery highlights the potential importance of hollow trees as habitat for species not previously recorded as using tree roosts. In addition, the discovery further identifies the need for consideration of changing fire management with the onset of warming and drying as part of climate change. Prevention of future conflagrations, as was witnessed during 2019/2020 fire season, should consider a range of options to help prevent the loss of valuable hollow-bearing habitat trees.

Forest islands in farmland provide vital roost trees year-round for giant and common noctule bats: Management implications

Forest islands in agricultural landscapes may be vital for biodiversity conservation, providing habitats for a variety of species, including bats. Our study focused on a forest island in NE Italy, where we observed mixed-species groups of giant (Nyctalus lasiopterus) and common (Nyctalus noctula) noctules roosting at the site. The giant noctule is highly endangered across Europe, and our findings shed light on its roosting preferences, providing key information to inform sustainable forestry practices that take this species into account. Using photographic methods and direct observation, we established that both common and giant noctules occur year-round in the forest island, with giant noctules giving birth, hibernating, and probably mating there. The bats preferred aspen trees and trees rich in cavities with high canopy closure and reduced sun exposure found in the forest interior, while they avoided forest edges. Rot cavities were frequently used, but we found no selection for cavity type, entrance height, or aspect. Despite the common belief that forestry activities in winter have negligible impact on bats, the felling of roost trees during this time can result in significant bat mortality since both common and giant noctules use these trees for hibernation. The number of cavities in a tree is a reliable predictor of a noctule roost, so it is advisable, year-round, to protect trees with cavities. Sustainable forestry practices should incorporate measures to provide roosting opportunities for bats, especially noctules. Our study only pertains to a single forest fragment. While our findings are novel and informative and highlight the conservation value of the forest island we studied, at this stage, they should not be generalized to all forest islands. We, therefore, encourage further large-scale studies to determine whether other forest islands are used similarly and to assess the broad-scale conservation implications of our work, particularly for threatened species such as the giant noctule.

Testing of Daubenton's Bat (Myotis daubentonii) Droppings for Field Behavioural Endocrinology

Measurement of faecal hormonal metabolites has become a widespread method in field endocrinology due to its non-invasiveness and ability to assess long-term stress; however, this approach has some limitations. We tested the potential of this assay for the Daubenton's bat (Myotis daubentonii), a small vespertilionid species (body mass 6–10 g), and we explored the relationship between cortisol and testosterone levels and dawn swarming, a signalling behaviour that occurs during roost-switching. Swarming was recorded using automated PIT-tag readers on the tree roosts of a maternity colony. In spite of absence of biological validation, our preliminary results demonstrate that field conditions of sample storage and small faeces weight do not interfere with hormonal measurement. We also found a positive correlation between individual levels of stress hormone (cortisol faecal metabolites) and swarming behaviour, but this should be interpreted with caution due to methodological shortcomings that need to be improved in future studies.

Evening Bats Captured in a Managed Wildlife Refuge Used Trees in a Human-Dominated Landscape as Maternity Roosts

Abstract Similar to many chiropteran species, pregnant and lactating evening bats Nycticeius humeralis form maternity colonies to bear and raise their pups. Although evening bat maternity roosts have been studied in other locations, knowledge gaps exist regarding maternity roost site selection on the Gulf Coast of Texas, United States; thus, our objective was to quantify maternity roost characteristics of evening bats in this region. We radiotracked 11 female and subadult evening bats to 9 roosts during June and July 2018 and 2019 captured in San Bernard National Wildlife Refuge (SBNWR). No transmittered bats roosted in SBNWR and instead all roosts were located 3.6–4.5 km from the same capture site, within an 81-ha residential area of a 5,496-ha city. Five of the nine roosts were located in tall, live, live oak trees Quercus virginiana and one roost was in a residential home. Colony size of bats occupying the roosts ranged from 16 to 500+ bats. All evening bats, including those on properties to which we were denied access, stayed in roosts for the full life of the transmitter (5–21 d) and no roost switching occurred. Although evening bats used SBNWR, potentially for foraging, results suggest trees in the residential area provided suitable maternity roost characteristics. A lack of roost switching may suggest a lack of available roost trees in SBNWR and residential areas or the selected roost trees were high quality. We recommend future studies increase sample sizes of evening bat roosts on the Gulf Coast of Texas, as well as assessing roost site selection of evening bats and monitoring bachelor colony and evening bat winter roost ecology.