Managing complex systems simply: understanding inherent variation in the use of roosts by Townsend's big-eared bat

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Variables driving the selection of roosts by Townsend's big-eared bat (Corynorhinus townsendii) and the degree of expression of roost fidelity by this species remain largely unknown. Current management and conservation practices assume that Townsend's big-eared bat is a habitat generalist with distribution limited by the availability of roosts. As such, it is supposed that this species exhibits strong roost fidelity across space and through time. Although reports of movement among and between roosts have been noted, it is unclear whether these movements were a result of human disturbance or part of some unknown, but normal, pattern of behavior. We investigated the validity of these assumptions by studying populations throughout the Great Basin of the western United States. Factors associated with roost selection were spatially variable throughout the project area. In addition, movement among roosts was common, with a high degree of intra- and inter-seasonal variation. However, at larger temporal, scales (i.e., across years), patterns of use became apparent. Differences in fidelity were noted between roost types, with use of caves more static (through space and time) than use of mines. We found that patterns of roost selection and fidelity were reflective of a combination of local conditions including roost availability, roost structure, surface associations, and the types of roosts available in the landscape. Based on these findings, we suggest that current management protocols be expanded and revised to account for the potential complexity of roost selection and use by this species.

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ELECTRONIC FILE - Zoology: Mammals

Full Citation: Sherwin, R. E., W. L. Gannon, and J. S. Altenbach. 2003. Managing complex systems simply: understanding inherent variation in the use of roosts by Townsend's big-eared bat. Wildlife Society Bulletin 31(1): 62-72.