Seasonal Use of Bridges by Rafinesque's Big-Eared Bat, Corynorhinus rafinesquii, in Southern Mississippi

Austin W. Trousdale, University of Southern Mississippi
David C. Beckett, University of Southern Mississippi

©Southeastern Naturalist


We conducted surveys of concrete bridges in southern Mississippi from 2000-2002 to determine the phenological pattern of use by Rafinesque's big-eared bat, Corynorhinus rafinesquii. The earliest dates on which we located maternity colonies were 9 March 2000, 20 April 2001, and 15 May 2002. Maternity colonies increased in size and abundance as spring progressed. pups were born in mid- to late May (first observed 12 May 2000, 15 May 2001, 27 May 2002) and nursed through midsummer (lactating females last captured 14 July 2000, 25 July 2001, 16 July 2002). Colony size and percentage of bridges occupied by bats declined in late summer. Colonies were absent during fall and winter, although we occasionally found solitary individuals during these seasons. Number of bats present under an occupied bridge ranged from 1 to 25. The mean number of individuals per occupied bridge was 4.6 (SD = 5.8) in 2000, 3.9 (SD = 5.0) in 2001, and 3.0 (SD = 4.4) in 2002. The mean number of adult females per maternity colony was 5.6 (SD = 3.1). Although we found males throughout the study period, females were largely absent from bridges outside of the maternity season, suggesting that much of the population used alternate roosts during this time.