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Pale Townsend’s big-eared bat

COTO1The pale Townsend’s big-eared bat (Corynorhinus townsendii pallescens, COTO) is one of five subspecies of Townsend’s big-eared bat that occurs broadly throughout the western United States into western Canada and central Mexico. All Arizona populations of this bat are considered to be this subspecies. COTO is an insectivorous bat feeding heavily upon moths and tends to roost from open ceilings of mine and cave features. Individuals range in size from 90 to 112 mm total body length weigh between 5 to 13 g. In southern Arizona this species does not migrate, but rather they hibernate in small groups in mines or caves with stable and cool temperatures. In summer, females may form maternity colonies of 12 – 200 bats; males roost apart from females and evidence suggests they are mostly solitary.

This subspecies is not federally listed, but is currently protected in several other western states. There are two other subspecies of Townsend’s big-eared bat that are federally listed as endangered, the Ozark and the Virginia big-eared bats. COTO have been found in roost sites on Pima County conservation lands in the Altar Valley, San Pedro Rive Valley, Cienega Valley, and Santa Catalina and Rincon Mountains.

Pima County’s bat monitoring objective is to monitor the occupancy, site condition, and associated management needs of a subset of roosts used by the Mexican long-tongued, Lesser long-nosed, California leaf-nosed, and Pale Townsend’s big-eared bats on Pima County open space lands. Monitored roosts will be those roosts that have particular importance to the local population of these four bat species. The County will also work towards documenting all of the known roosts sites for these species that are located on County lands, though not all will be chosen for additional monitoring efforts. Where possible and relevant, results from these inventory and monitoring efforts will be used to guide the management (i.e., gating) and/or restoration of key features that will benefit these and other bat species.

Photo by National Park Service