Use of Culverts as Diurnal Roosts by Tricolored Bats (Perimyotis subflavus) in East Texas: Exploring Seasonality and Spatial Resource Selection

Rest is a state of dormancy characterized by decreased responsiveness and is a crucial behavior of all organisms, especially mammals. Understanding the places in which organisms choose to rest can help inform management decisions and enhance conservation efforts. Texas has the highest diversity of bats of all states in the United States. Many bats such as Perimyotis subflavus (Tricolored bat), Eptesicus fuscus (Big brown bat), Myotis austroriparius (Southeastern myotis), Corynorhinus rafinesquii (Rafinesque big-eared bat), and Tadarida brasiliensis (Mexican Free-tailed bat) roost in man-made structures such as culverts and bridges and have increasingly done so over the last 100 years. Bats that can adapt to these altered environments may have a selective advantage over those that cannot, potentially influencing the dynamics of bat populations. In chapter two, I explored differences between summer and winter use of culverts as diurnal roosts by bats in eastern Texas. I found that P. subflavus were roosting in east Texas culverts at significantly greater frequencies and abundances during winter than in summer. Winter abundances were also found to be highest in culverts with lower internal wall temperatures. In chapter three, I investigated selection of culverts as diurnal roosts in eastern Texas at three different scales: culvert, landscape, and ecoregion. I found that culvert length was the most important characteristic related to diurnal roost selection for P. subflavus. Mixed forests influenced roost selection as greater proportions surrounding culverts positively influenced the frequency of P. subflavus occurrences and their abundances. The South Central Plains ecoregion was found to be significantly related and to positively influence P. subflavus abundance. This research provides an in-depth account of roosting ecology and selection of artificial structures as roosting sites by bats.