Roosting affinities of Townsend's big-eared bat (Corynorhinus townsendii) in northern Utah

Abstract

We surveyed abandoned mines, caves, and bridges to identify habitat preferences of day-roosting Townsend's big-eared bat (Corynorhinus townsendii) in northern Utah. Of 820 sites surveyed (676 mines, 39 caves, and 105 bridges), 196 (23.9%) were occupied by C. townsendii. Caves were the most frequently used type of roost (84.6%), 21.2% of abandoned mines were used as day roosts, and no bridges were used. Bats occupied mines and caves at lower available elevations (1,350-2,440 m), which were associated with sager brush-grass steppe, juniper woodlands, and mountain brush vegetation. In general, roosts with single low (< 1.5 m height) entrances were more likely to be occupied than those with multiple or tall entrances. Day roosts typically were subject to little disturbance by humans. Aspect and width of entrance, stability and complexity of interior, presence of multiple entrances, length of tunnel, amount of internal air flow, presence of multiple levels, and presence of internal water were not associated significantly with occupancy; however, maternity colonies tended to be located in large complex sites with multiple openings.