Multi-Scale Roost-Site Selection by Evening Bats on Pine-Dominated Landscapes in Southwest Georgia

Abstract

Bats likely incorporate multi-scale criteria when selecting roost sites, which may change across different landscapes. During summers 2002 and 2003, we used radiotelemetry to investigate day-roost selection of evening bats (Nycticeius humeralis) at multiple scales in mature longleaf (Pinus palustris; natural) and intensively managed loblolly pine (P. taeda; managed) landscapes in the Gulf Coastal Plain of Georgia, USA. We used Akaike's Information Criterion (AIC) to evaluate models describing roost-site selection at the tree, plot, stand, and landscape scales. Evening bats on the natural site selected day-roosts based on tree, plot, and landscape characteristics, but bats on the managed site selected day-roosts only at the tree and plot scale. We hypothesize that greater availability of roosting structures (i.e., abundant large trees and snags) throughout the natural site allowed evening bats to select day-roosts that had favorable landscape characteristics (i.e., closer to water and foraging sites), possibly providing benefits from reduced commuting costs. On the managed site, the relatively young age structure of stands resulted in less-abundant roosting structures throughout the landscape, resulting in selection only at the tree and plot scales. Evening bats appeared to select day-roosts that provide energetic benefits when landscape conditions permitted, however, replicated studies are needed to examine the relationship between energetics and roost availability. Land management on pine landscapes of the southeastern United States that promotes large trees, retention of snags, and an open midstory appears to provide abundant roost structures for evening bats. On managed landscapes, roost sites for evening bats may be provided by retention of forked-topped pines in managed stands and by allowing maturation and senescence of trees in set-aside areas, such as streamside management zones, to promote snag and cavity formation.