Baseline Data on Overwintering Bats and Roosts in Texas
Abstract
New or introduced infectious diseases can have detrimental effects on wildlife populations, including reduction of population size of some species, and even extinction. White-nose syndrome (WNS), a bat disease caused by a fungus (Pseudogymnoascus destructans), has led to substantial declines in population size of some bat species in eastern North America. As a result of the spread of P. destructans in Texas, WNS was documented in Texas in spring 2020. To investigate site-specific landscape and environmental predictors of bat presence and abundance, I collected data on two WNS-affected species (tri-colored bat (Perimyotis subflavus) and cave myotis (Myotis velifer)). I collected data from 450 sites (145 caves and 305 culverts) from January–March 2016, November–February 2016–2017, and October–March 2017–2018/2018–2019. Furthermore, I used data collected from 86 hibernacula (55 caves, 30 culverts, and 1 tunnel) to investigate site-specific landscape and environmental predictors of P. destructans presence. Using zero-inflated Poisson regressions, I found that predictors of bat presence and abundance differed between bat species at the state level. Tri-colored bat abundance increased as slope, elevation and distance to nearest water source decreased, as well as sites with easterly aspects. Cave myotis abundance increased as slope, elevation, and distance to water increased, as canopy cover decreased, and at sites with easterly aspects. As tri-colored bats and cave myotis were only present in particular ecoregions, I conducted individual logistic regressions using data from these ecoregions for each species to determine site-specific landscape and environmental factors predicting bat presence. My analyses of combined presence/absence data for the ecoregions in which each species was documented suggested that there were no site-specific landscape and environmental predictors of tri-colored bats and cave myotis. However, individual analyses for each ecoregion where tri-colored bats were present or where cave myotis were present suggest that there are differences in predictors based on location within the state (i.e., ecoregion). My research will aid in the management of WNS-afflicted bat species by better understanding their overwintering distribution. Further, this baseline data will play a critical role in developing management plans for both biologists and landowners.
Citation
Meierhofer, Melissa Beth (2020). Baseline Data on Overwintering Bats and Roosts in Texas. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /192516.