Summer Indiana bat ecology in the southern Appalachians: An investigation of thermoregulation strategies and landscape scale roost selection

In the southern Appalachians there are few data on the roost ecology of the federally endangered Indiana bat (Myotis sodalis). During 2008-2012, we investigated roosting ecology of the Indiana bat in ∼280,000 ha in the Great Smoky Mountains National Park, Cherokee National Forest, and Nantahala National Forest in the southern Appalachians Mountains of Tennessee and North Carolina. We investigated 2 aspects of the Indiana bat's roosting ecology: thermoregulation and the extrinsic factors that influence body temperature, and landscape-scale roost selection. To investigate thermoregulation of bats at roost, we used data gathered in 2012 from 6 female Indiana bats (5 adults and 1 juvenile) to examine how reproductive condition, group size, roost characteristics, air temperature, and barometric pressure related to body temperature of roosting bats. We found that air temperature was the primary factor correlated with bats' body temperatures while at roost (P < 0.01), with few differences detected among reproductive classes in terms of thermoregulatory strategies. To understand how Indiana bats select roosts on a landscape-scale, we created a presence-only model through the program MaxENT using 76 known roost locations to identify areas important to summer roosting habitat within our study area and to identify important landscape-scale factors in habitat selection. The final model showed that Indiana bats selected roosts on the upper portion of ridges on south facing slopes in mixed pine-hardwood forests at elevations of 260-700 meters. Unfortunately, due to small sample size and the large effort required to fully investigate thermoregulation of Indiana bats in the southern Appalachians, we only were able run correlations with temperature data, and further investigation is needed to make concrete conclusions. However, the new advancements in resolution of landscape cover data and new programs in spatial modeling have enabled us to produce a large scale spatial model for identifying Indiana bat summer roosting habitat within our study area. Our findings have added to our understanding of Indiana bat roosting ecology, particularly in the southern Appalachian Mountains, and will aid land managers in effective management for this federally endangered species.