Boyles, Justin. 2004. Master's thesis: A comparison of summer and winter roosting habitat and behavior of evening bats (Nyctieceius humeralis) in Missouri. Missouri State University. Springfield, Missouri.

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.