Effects of reproductive condition, roost microclimate, and weather patterns on summer torpor use by a vespertilionid bat

Johnson, Joseph S.; Lacki, Michael J.

doi:10.1002/ece3.913

Cited by 39 publications

(43 citation statements)

References 37 publications

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“…We elected to not categorize each T sk reading as normothermic or torpid due to difficulties in accurately recognizing torpor using temperature data (Boyles et al 2011, Brigham et al 2011, Johnson and Lacki 2014. Each transmitter was calibrated by the manufacturer, allowing us to create unique polynomial equations from which we could convert pulse rates into T sk measures.…”

Section: Temperature-sensitive Radio-telemetrymentioning

confidence: 99%

“…Studies examining the use and thermal benefits of buildings in areas with alternative roosts are uncommon but are needed to evaluate the conservation value of buildings for bat populations (Lausen and Barclay 2006, Law and Chidel 2007, Johnson and Lacki 2014. Bats are frequently evicted from buildings, but the removal of these bats, especially maternity colonies, is a conservation concern as WNS continues to cause mortalities in cave-hibernating bat populations across the continent.…”

Section: Introductionmentioning

confidence: 99%

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Buildings provide vital habitat for little brown myotis (Myotis lucifugus) in a high‐elevation landscape

et al. 2019

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Bats in North America are currently experiencing dramatic population declines due to the disease white-nose syndrome. The long-term viability of vulnerable species requires recognition of critical habitats, including those also occupied by humans. Our study aimed to quantify the importance of buildings to little brown myotis (Myotis lucifugus) in Yellowstone National Park, a high-elevation landscape with relatively few human structures and abundant alternative roosting habitat. We measured roost preferences and thermoregulation in adult male and female bats roosting in buildings, trees, and rocks using temperature-sensitive radio-transmitters. We also studied microclimates within each roost type for comparison to roost preferences. We found reproductive females roosting in building attics on 84% of all possible days, while males roosted exclusively in rock crevices or in trees. This dichotomous roosting pattern reflected differences in roost microclimates. All roost types buffered bats from daily minimum ambient temperatures; however, buildings were more insulated from low ambient temperatures during the middle of the maternity season. Male bats roosting in rocks and trees predominantly thermoconformed to roost temperatures, while females roosting in buildings sustained higher body temperatures than males throughout the day. Pregnant and lactating females also used torpor frequently, with skin temperatures reaching <10°C, and a gestation period lasting 49-89 d. These results show that cool summer temperatures at high elevations present an energetic challenge to little brown myotis. Buildings provide critical habitat for reproductive females and likely allow for larger populations than would be possible in their absence, making these roosts a priority for long-term conservation of this declining species.

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Section: Temperature-sensitive Radio-telemetrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Buildings provide vital habitat for little brown myotis (Myotis lucifugus) in a high‐elevation landscape

et al. 2019

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“…The seasonal differences in roost selection observed between pregnant and lactating and non‐reproductive females indicated these groups of bats roosted under differing habitat conditions. Many studies have demonstrated differences among reproductive condition classes in thermoregulatory strategies within bat species, especially for non‐reproductive females because they are not constrained by the demands of pregnancy and lactation (Hamilton and Barclay , Cryan and Wolfe , Rambaldini and Brigham , Johnson and Lacki ). We hypothesize that a comparable pattern may exist for northern long‐eared bats; however, the non‐reproductive females in our study were from spring staging, not the maternity season, and could possibly reflect behavior of pregnant females in early stages of gestation.…”

Section: Discussionmentioning

confidence: 99%

“…By roosting in large‐diameter trees, bats likely encounter a more predictable micro‐environment during the day, potentially facilitating lower body temperatures, reduced metabolic rates, and increased energy savings. Bats in this scenario, however, could also be less likely to use passive rewarming as an energy saving strategy to arouse from torpor (Lausen and Barclay ; Rambaldini and Brigham ; Johnson and Lacki a ,). Pregnant and lactating females demonstrated a preference for roost trees in stands with lower basal areas and live tree densities than randomly selected snags (i.e., stand model).…”

Section: Discussionmentioning

confidence: 99%

Tree roosts of northern long‐eared bats following white‐nose syndrome

Thalken

Lacki

2017

J Wildl Manag

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Spring emergence and summer maternity seasons are critical to long‐term survival of cave‐hibernating bats inhabiting geographic regions affected by white‐nose syndrome (WNS). White‐nose syndrome reached cave‐hibernating populations of bats in Mammoth Cave National Park (MCNP), Kentucky, USA, in 2013, with significant declines in several species of bats that hibernate in MCNP during winter 2014–2015, including the northern long‐eared bat (Myotis septentrionalis). To assess behavior and roost selection of individuals surviving to spring emergence and the summer maternity season, we radio‐tracked 26 northern long‐eared bats captured at various locations with differing habitat conditions in MCNP during 2015 and 2016. We tracked bats daily to identify roosting sites and patterns in use of roosts, describe habitat conditions associated with roosting sites, and quantify variation in size of colonies occupying roost trees. The average number of bats emerging from roost trees (3.58 ± 0.57 [SE]) was low compared with estimates for the species in studies completed pre‐WNS. Adult female bats selected trees within 6 roost areas with no overlap in use of roost areas between non‐reproductive females in spring and pregnant and lactating females in summer. Variation in roost tree and surrounding forest characteristics occurred across sex and reproductive condition classes, with males and pregnant and lactating females roosting at higher landscape positions than non‐reproductive females. Comparisons of roosting habitat models demonstrated the torpor model (decay class, stem diameter, canopy cover) to be parsimonious, regardless of sex and reproductive condition class, suggesting importance for choosing roost trees that facilitate use of daytime torpor. Such a strategy would promote energy savings and be consistent with behaviors anticipated for bats vulnerable to WNS effects during winter hibernation because these bats are potentially compromised in health and physiologic condition upon emergence from hibernation in spring. We encourage land managers responsible for roost trees of northern long‐eared bats to consider seasonal and landscape‐level variation in roosting habitat needs of these bats. © 2017 The Wildlife Society.

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“…Rafinesque's big-eared bats have broad, short, rounded wings which allow them to glean insects from vegetation and other surfaces, but also increase their risk of extinction due to higher flight costs and limited abilities to disperse over large distances (Safi and Kerth 2004). In the northern portion of their range, they roost in a variety of roosts including caves, rock shelters, artificial roosts, and tree cavities (Johnson and Lacki 2014) but in Coastal Plain regions, they are closely associated with mature bottomland hardwood forests (Bat Conservation International and Southeastern Bat Diversity Network 2013). These forests experienced significant declines (~80%) during the 18th, 19th, and early 20th centuries due to conversion to agriculture (Wear and Greis 2002).…”

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confidence: 99%

Adaptive response to land-use history and roost selection by Rafinesque’s big-eared bats

Loeb

2017

Journal of Mammalogy

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Although habitat loss and degradation are major contributors to species declines, some species are able to adapt to changes in land use by selecting different habitats or structures in disturbed areas than they do in more pristine habitats. Bats are particularly vulnerable to changes in land use due to their dependence on specific habitat types and structures. The objective of this study was to determine how selection and use of roost trees, and niche breadth of Rafinesque's big-eared bats (Corynorhinus rafinesquii) varied with land-use history. I examined use and selection of roosts at 3 bottomland hardwood sites that varied in amount and time since timber harvest. Fortynine transects were established as a means of searching for bats in trees with basal cavity openings and were surveyed 2-9 times. Bats at the most-disturbed sites exhibited the broadest niches, using a greater number of tree species and habitat types, although bats at the least-disturbed site used a broader range of cavity volumes. Cavity characteristics were the primary factors governing roost selection by Rafinesque's big-eared bats, but selection varied among sites. Probability of use increased with increasing cavity volume for bats at all sites, but bats at the most-disturbed site primarily used trees in the smallest cavity volume class, whereas bats at the least-disturbed site primarily used trees in the largest cavity volume class. Results of this study suggest that Rafinesque's bigeared bats can adapt to a range of habitat conditions if trees with large cavities are available. However, future studies need to determine the long-term viability of this species in disturbed habitats.

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Effects of reproductive condition, roost microclimate, and weather patterns on summer torpor use by a vespertilionid bat

Cited by 39 publications

References 37 publications

Buildings provide vital habitat for little brown myotis (Myotis lucifugus) in a high‐elevation landscape

Buildings provide vital habitat for little brown myotis (Myotis lucifugus) in a high‐elevation landscape

Tree roosts of northern long‐eared bats following white‐nose syndrome

Adaptive response to land-use history and roost selection by Rafinesque’s big-eared bats

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