A Comparison of Summer and Winter Roosting Habitat and Behavior of Evening Bats (Nycticeius Humeralis) in Missouri

Date of Graduation

Spring 2004

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Lynn Robbins

Abstract

I radio-tracked 13 evening bats (Nycticeius humeralis) to 34 trees during the summer of 2003 and 11 evening bats to 29 trees during the winters of 2003 and 2004. I captured males in every month of the year and I provide capture and radio-telemetry evidence that females are also year-round residents of southwestern Missouri. Evening bats chose trees in late stages of decay during the summer when compared to available trees at two geographic scales, but during the winter they roosted in a higher proportion of live trees. During both the summer and winter, evening bat roosts were located closer to other known roosts than were randomly selected points, indicating a clumped distribution of roosts. Comparisons of summer and winter trees suggest that habitat characteristics such as surrounding tree density, canopy height, and distance to the nearest water source are more important than tree characteristics in explaining variation between roosts used in the two seasons. Winter roost trees were located in areas with lower canopies and higher densities of trees. Those habitat attributes would likely cause problems with acoustic clutter when the leaves are on the trees during the summer. Approximately 55% of the study area is under a periodic burn management plan, but all roost trees were located in this portion of the study area, possibly due to the lower density of trees in the subcanopy. I also report interesting roosting behaviors utilized by N. humeralis, including the use of a subterranean roost by one individual during the winter.

Keywords

Chiroptera, evening bats, Nycticeius humeralis, roosting, mist nets, radio-telemetry

Subject Categories

Biology

Copyright

© Justin G. Boyles

Citation-only

Dissertation/Thesis

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