Date of Award

Fall 12-1-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

John O. Whitaker Jr.

Second Advisor

George S. Bakken

Third Advisor

Peter E. Scott

Abstract

Two species with different ecologies and natural histories use different morphological characteristics and thermoregulatory strategies to survive seasonal environmental changes. The purpose of this project was to investigate two such species, the eastern red bat (Lasiurus borealis) and big brown bat (Eptesicus fuscus). Red bats roost in the foliage of trees and occasionally leaf litter and have dense fur, as well as a furred interfemoral membrane. These two species differ in their morphology and roosting ecology in that big brown bats are generally larger with less dense fur, no fur on the interfemoral membrane, and are less exposed to environmental conditions as they typically make use of buildings, tree hollows, and caves. Thermal conductance (K) of summer and winter dorsal pelage from specimens of both species and the interfemoral membrane of red bats was measured with a heat flow plate in a wind tunnel. There were significant seasonal differences in K of the dorsal pelage for red bats, but not for the interfemoral membrane. Seasonal differences in K for the big brown bat were not significant, but K values were significantly higher than red bats in both seasons. Changing pelage insulation allows both species to dissipate heat during summer and conserve heat in winter (with increased metabolic rates) when ambient temperature is above freezing. However, these bats must also rely on other mechanisms largely dictated by their respective ecology and natural history in order to survive.

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