Foraging-habitat selection by bats at an urban–rural interface: comparison between a successful and a less successful species

We compared habitat use of two sympatric species of bat in a rural area undergoing suburban development. The two species are similar in diet and foraging-habitat use but differ in current roosting habitat, and exhibit contrasting regional population trends. Evening bat, Nycticeius humeralis (Rafinesque, 1818), populations are declining in central Indiana, whereas big brown bat, Eptesicus fuscus (Beauvois, 1796), populations are increasing. We assessed habitat selection by 22 adult female bats using radiotelemetry and compositional analysis. Eptesicus fuscus used several roosts across the study area; all but one roosted in human-made structures. Nycticeius humeralis clustered roosts within a small group of woodlots; all roosted in tree cavities. Eptesicus fuscus foraged for longer periods of time and nonreproductive individuals of this species had larger foraging ranges than N. humeralis. Both species foraged primarily in agricultural and wooded areas. During foraging, N. humeralis showed greater foraging-site fidelity and a stronger selection for agricultural and wooded areas than E. fuscus. We suggest that N. humeralis in our study area is probably more sensitive to suburban development near their roosts than E. fuscus.