Differential selection of roosts by Eastern Small-footed Myotis relative to rock structure and microclimate

Roost selection by insectivorous bats in temperate regions is presumably influenced by roost microclimates in relation to thermoregulatory strategies, but few studies have included temperature measurements in habitat selection models. Rocky landscape features are an important source of roosts that provide both shelter from predators and beneficial microclimates for bats. Most information about rock-roosting bats is derived from western North America. We studied microhabitat selection by Eastern Small-footed Bats (Myotis leibii) on natural talus slopes and human-made stone structures in the Appalachian Mountains of Virginia and New Hampshire, relative to thermal and structural characteristics of rock crevices. Roosts were located with a combination of radio-telemetry and randomized visual surveys. Roost switching behavior and structural characteristics of roosts did not appear to be influenced by the methods we used to locate roosts. Compared to random crevices, both sexes selected crevi..., Free-ranging Eastern Small-footed Bats were located in their roost sites either using radio-telemetry or with visual searches. Roosts were categorized according to what could be inferred about the occupants when viewed from outside the crevice during visual searches, or based on physical examination in the case of captured individuals. For each roost, we measured the length, depth and height of the upper and lower rocks that formed the crevice, and the length, depth, width and orientation (categorized as horizontal, diagonal, or vertical) of the crevice. To reduce the number of variables we needed to model, we used a Principal Components Analysis to describe variation in the six rock variables, and we saved the resultant component scores as latent variables (PC 1 and PC2); these corresponded to overall size of the upper and lower rocks, respectively. Strong positive component scores indicate the largest rocks. We also recorded temperatures for a subset of crevices and for nearby ambient..., The data files are .csv format, which are compatible with most spreadsheet software packages. Â