Potential for Monitoring Eastern Small-footed Bats on Talus Slopes

Abstract

Typical efforts to monitor bat populations in North America rely on winter hibernacula counts, but this method may be ill-suited for Myotis leibii (Eastern Small-footed Bat). Timing of reproduction, migration, and hibernation in this species also are poorly understood. We piloted novel techniques to monitor Small-footed Bats during the nonhibernation period, including catching bats in mist-nets placed directly on talus slopes, visually searching for roosting bats, surveying randomly distributed quadrats to estimate population size, and using skin temperature to study thermoregulation and seasonal activity. We efficiently documented bats with mist-nets and visual searches; the animals used crevices near the surface of talus slopes from early March until the end of October. Estimates from quadrats suggested one 3-ha talus slope had a maximum population of 196–343 bats. Use of torpor varied seasonally, but was similar between sexes. In mid-March, bats exhibited a hibernation-like pattern of torpor, hinting at the possibility that they may also overwinter on talus slopes. Monitoring of Small-footed Bats on rock outcrops during summer could resolve uncertainty about population trends. Thus, techniques described herein should be tested at suitable habitats in other parts of the range of Small-footed Bats.