GRILLIOT, M.E.*; BURNETT, S.C.; MENDON�A, M.T.; Auburn University, Auburn; Clayton College &State University, Morrow; Auburn University, Auburn: Does reproductive state affect echolocation signals in Eptesicus fuscus: a preliminary study?

Ultrasound is a widely used acoustical method for social communication, as well as for navigation and foraging. Although bats are well known for their use of ultrasound for the latter function, there is presently limited evidence for its use in the former function. Studies have indicated its use in mother-young interactions, and there is some evidence that male and female vocalizations differ in some species. However, no studies have explored its use in courtship and mating. We have a captive colony of big brown bats housed in environmental chambers that allow us to alter temperature and photoperiod in order to mimic seasonal changes and induce mating behavior. This offers us a unique opportunity to investigate seasonal differences in the echolocation calls of big brown bats. We have recorded the echolocation calls of eight adult female and eight adult male big brown bats in different reproductive states. Thirty-four parameters (e.g. duration, starting and ending frequency of fundamental, frequency of maximum amplitude for fundamental) for each echolocation call were analyzed for seasonal differences, sex differences, and individual distinctiveness. Results from these studies could provide insight into the role of echolocation (if any) in big brown bat mating systems.