Date of Award

Spring 5-1-2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Life Sciences

First Advisor

John O. Whitaker Jr.

Second Advisor

C. Mark Cowell

Third Advisor

Marion T. Jackson

Abstract

A study concerning the natural history and roosting ecology of the eastern pipistrelle, Pipistrellus subtlavus, was conducted from 1997 to 2000, in southern Vigo County, Indiana. 111 Females began forming pre-maternity colonies during early May, and parturition began during late June. Pre-maternity colonies averaged 3.7 ± 1.9 individuals, and maternity colonies averaged 4.4 ± 2.4 individuals. Young pipistrelles first became volant during the third and fourth weeks of July. Pipistrelles were located in 59 roost trees. All roosts were located in foliage, either in clusters of dead leaves (n = 40) or in live foliage (n = 19). Oaks (Ouercus species) and box-elders (Acer negundo) were preferred as roost tree species. Trees averaged 22. 8 ± 7 .2 m tall, while leaf roosts averaged 17 .1 ± 6.2 m from the ground, and 62.4 ± 27.7% of the general canopy height. Canopy closure was 42.1 ± 29.5%, and leaf roosts had low percent clutter obstructing the area immediately below the roost (10.7 ± 20.0%). Roost trees were located 143.0 ± 200.2 m from water, and 43.9 ± 41.9 m from the nearest forest edge. Reproductive females exhibited a higher degree of fidelity to their roosts than non-reproductive females in terms of roosts used (2. 8 ± 1. 7 and 4. 5 ± 1. 8, respective! y ), roost switches (2.3 ± 1.9 and 4.3 ± 1.9, respectively), and maximum consecutive days spent at a roost tree (6.0 ± 2.7 and 3.1 ± 1.9, respectively), during the period bats were monitored (9.1 ± 2.2 days). IV Reproductive females differed from non-reproductive females in terms of roost choice (i.e. characteristics of roost trees). Reproductive females used trees and foliage which were located further below the general canopy, nearer to trees as tall or taller than the roost tree, nearer to water, and further from a forest edge, relative to those used by non-reproductive females. Roosting in trees and foliage which were located further below the forest canopy, nearer to tall trees, and further from a forest edge, may have provided reproductive females with protection from the cooling effects of wind and rain, and therefore may have provided a more suitable microclimate.

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