Date of Award

Spring 5-1-2002

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Advisor

John O. Whitaker Jr.

Second Advisor

Marion T. Jackson

Third Advisor

Peter E. Scott

Abstract

The purpose of this study was to look at possible methods of prey-resource partitioning between two sympatric species of bat that have similar diets: the evening bal, Nycticeius humeralis, and the big brown bat, Eptesicus fuscus. Thirty-four adult female bats were radio tracked during this study: 11 evening bats and 11 big brown bats near a suburb oflndianapolis, IN in 2001, and 11 evening bats and l big brown bat in the bottomland forest of Prairie Creek, IN in 1999 and 2000. Habitat use and foraging patterns were evaluated using radio-telemetry and a geographic information system (GIS). Habitat selection was assessed using compositional analysis. Insects were sampled using non-attractant traps. At the Indianapolis site, big brown bats spread their roosts across the study area; all but one roosted in man-made structures. Evening bats clustered their roosts within a small group of woodlots; all roosted in the cavities of trees. Big brown bats had a larger foraging range and foraged for a longer period of time when compared to evening bats. They also changed foraging sites between nights and used all habitats according to their availability. Evening bats foraged in the same sites between nights, avoided residential areas and showed a preference for agricultural and wooded areas during foraging. The larger foraging range and ability to use all the habitats in the area should allow big brown bats to avoid interspecific competition with evening bats by changing iv foraging locations and partitioning the sources of prey. The location of some prey items in open habitat, and the preference for wooded areas within their foraging range, suggests that evening bats are foraging along wooded edges. Residential areas may represent a barrier to evening bats during their nightly foraging flights and restrict the areas where they are able to roost.

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