ASSESSMENT OF THE STATUS OF THE TOWNSEND'S BIG-EARED BAT IN CALIFORNIA.
Leila S. Harris; Department of Wildlife, Fish, and Conservation Biology; University of California, Davis, CA, 95616; (650) 455-6184; leiharris@ucdavis.edu; Michael L. Morrison, Joseph M. Szewczak, Scott D. Osborn
Townsend's big-eared bat (Corynorhinus townsendii, COTO) is a California Species of Special Concern. Pierson and Rainey (1998) conducted the only previous statewide field study of its status. We assessed COTO's current California distribution by revisiting previously-known roosts and other sites. We compiled roost information by searching literature and databases and contacting biologists/managers for unrecorded sites. Our sample framework was NABat's 10km by 10km grid. We surveyed 2 winters and 3 active seasons during 2014-2017. We sampled 304 grid cells (206 summer, 98 winter) and surveyed 620 potential roosts. We located COTO at 209 active season non-maternity roosts, 84 maternity roosts, and 80 hibernacula. Half of maternity roosts were in mines, 29% in caves, and the remainder in other structures. 58% of roosts had sign of disturbance. We confirmed COTO at 53 of 80 historical summer sites and 37 of 63 historical winter sites. We determined status of two-thirds of Pierson and Rainey's sites. Of those, about half remained active. That study reported 39-43 maternity colonies. We documented 84; however, it is unlikely this represents population expansion. Further, decadal persistence does not equate to stable populations. COTO remains well-distributed in California, but suitable roosts will continue to decrease unless actively managed.
Ecology and Conservation of Bats II   Student Paper