The lab is tackling many projects associated with mammal conservation, many focusing on bats in the southeastern US. These projects currently include:
Hibernation behavior of tri-color bats in non-traditional hibernacula
While tri-colored bats (Perimyotis subflavus) are severely impacted by WNS throughout their range, we have yet to confirm WNS from any tri-colored bat from any location in Texas, despite the presence of the fungus that causes WNS throughout the state. Given we have observed variation in hibernation behavior in tri-colored bats, it is critical to understand the impacts these behaviors have on hibernation energetics, pathogen dynamics, and the mechanisms that allow Texas tri-colored bats to avoid WNS. Our long-term goal is to understand the bioenergetics and roosting requirements of tri-colored bat i in east Texas and thereby develop the best possible conservation approaches for this unique population of bats that may act as a source population. This study will help to not only understand hibernation in this specific location, but also shed light on the flexibility of hibernation behaviors across all hibernators in mild and variable climates. To achieve these goals, we are using passive monitoring techniques and bioenergetic modeling that we will compare to previous work from bat species (tri-colored and others) in colder climates. More broadly, this project will provide information about the common traits of apparently unaffected populations, and thus will help explain differential susceptibility on an individual and species level. This work is lead by graduate student Leah Crowley.
Microclimates associated with roost trees of tri-colored bats (Perimyotis subflavus)
Previous work from the lab determined that roost tree selection of tri-colored bats is driven by roost tree height. We hypothesize that this is due to the thermoregulatory benefits of microclimate variance associated with taller trees. We will test this hypothesis by quantifying microclimates along a vertical gradient on known roost trees and comparing to microclimates of unused trees. We hope to eventually find microclimate gradients and measure body temperature of tagged bats to determine heterothermic responses to these gradients. This work is lead by Mammal Project Coordinator Sarah Zirkle.
Impacts of white-nose syndrome on juvenile body mass
Research has shown shifts in the peak proportion of pregnant females to later in the summer in areas where WNS has devastated susceptible populations. These shifts are attributed to the increased energetic demands of WNS during winter and can be problematic if juveniles lack adequate time to gain fat stores before hibernation. In locations where winter is short and mild, and thus energetic demands of hibernation are low, WNS-susceptible species should not delay reproduction at the same rates compared to areas with longer, more intense winters. Therefore we predict a shift in the timing in which post-WNS juveniles reach their maximum adult weight before hibernation. Alternatively, populations build up fat store relative to winter duration and thus we would see the same trends in reproductive condition and juvenile body mass in WNS-susceptible species, regardless of winter impacts. This work is lead by wildlife research ecologist Sarah Krueger.
Testing the thermal suitability of bat boxes and use in response to temperature
Many bat species use man-made structures for nightly roosts due to habitat loss from human disturbance. Homeowners can provide bat houses to reduce human-bat conflicts, but recent research suggests that these bat houses often over-heat during the summer due to size, placement, and over-crowding, ultimately leading to mortality in vulnerable bat species. Work has been done to quantify the thermal environment of different bat house designs using easily deployed data loggers; however, these temperature sensors can misrepresent the thermal quality of habitats as they lack the ability to include the influence of other microclimate factors experienced by the animal (e.g., convective cooling, radiative heat from other bats, etc.) nor the thermal properties of the animal afforded by traits such as fur, hair, and blubber. Instead, taxidermic mounts consider these factors in their measurement of the thermal environment by incorporating real animal fur and tissue. Additionally, though we have begun research to define both the temperature limits of bats as well as what bat box designs can maintain temperatures within these limits, we have yet to assess how bats respond to temperature of bat boxes. The objectives of this study are 1) quantify microclimate conditions of different bat box designs using taxidermic mounts, 2) assess the thermal suitability of different bat box designs to remain within the thermal limits of North American bat species, and 3) determine fine-scale use of bat boxes in response to temperature per species. We also aim to include a community outreach component to this project, where we will work with public and private landowners to assess thermal suitability and bat use of their personal bat boxes. The results from this study will help mitigate human-bat conflicts with the understanding of how artificial roosts may not be as suitable as once thought and assessing how bats respond to these stresses. This work is currently funded by an APSU Research Support Grant.