Comments: Maternity and hibernation colonies typically are in caves and mine tunnels. These bats prefer relatively cold places for hibernation, often near entrances and in well-ventilated areas. In California, most limestone caves are too warm for successful hibernation; solitary males and small groups of females are known to hibernate in buildings in the central part of the state. These bats do not use crevices or cracks; they hang from the ceiling, generally near the zone of total darkness (Schmidly 1991). Night roosts include caves, buildings, and tree cavities. In Utah, caves were preferred as day roosts in summer (85% of surveyed caves used), as well as abandoned mines (21% surveyed were used); no bridges were used (Sherwin et al. 2000). However, all six known maternity colonies in coastal California are in old buildings (5) or in a cave-like feature of a bridge (1) (Fellers and Pierson 2002).
Throughout much of the known range, these bats commonly occur in mesic habitats characterized by coniferous and deciduous forests (Kunz and Martin 1982), but they occupy a broad range of habitats (e.g., see Handley 1959). In California and Washington, they are known from limestone caves, lava tubes, and human-made structures in coastal lowlands, cultivated valleys, and nearby hills covered with mixed vegetation (Handley 1959). Feller and Pierson (2002) studied a population in Point Reyes National Seashore, California, that foraged along the edges of redwood and Douglas-fir forests and woodlands, primarily along the edges of riparian vegetation. Individuals avoided grassland wherever possible, even while commuting to foraging grounds.
On the West Coast, Townsend's big-eared bats are found regularly in forested regions and buildings, and in areas with a mosaic of woodland, grassland, and/or shrubland. They are recorded from pine-fir-hemlock-broadleaf deciduous forest in western Oregon, and from the edge of spruce-fir forest in Colorado (see Handley 1959). In Utah, day roosts were associated with sagebrush steppe, juniper woodlands and mountain brush vegetation at lower available elevations (1350-2440 meters; Sherwin et al. 2000). In Texas, habitat ranges from desert scrub to pinyon-juniper woodland, consistently in areas with canyons or cliffs (Schmidly 1991). In New Mexico, most have been captured in evergreen forests during warm months, least commonly captured in xeric shrublands (see Kunz and Martin 1982). In Arizona, habitats include desertscrub, in shelters in desert mountains (where infrequent), oak woodland, pinyon-juniper, and conifer forests (Hoffmeister 1986). In Kansas and Oklahoma, these bats are apparently restricted to riparian communities and nearby gypsum caves in the mid-grass prairie region. Generally they are uncommon in prairies and extreme desert, although they occur in the lower elevations of the arid plateau and desert ranges of northcentral Mexico and the arid valleys south of the transverse volcanic belt. They are known in Mexico mostly from relatively arid regions (e.g., grassy hills with nearby pine-oak woodland) but also from more humid localities with oak, pine, juniper, cypress, madrone, and manzanita (Handley 1959). Ozark and Appalachian populations inhabit caves mostly in oak-hickory forest (Handley 1959).
These nimble bats are able to fly through narrow passages (Hoffmeister 1986).
Females gather in small nursery colonies in the warm parts of caves or mines, sometimes in buildings (western U.S.). Individuals generally return to the same maternity roost in successive years. In Oregon, both sexes apparently use a series of interim roost sites between emergence from hibernation and the time females enter into maternity colonies, with little individual fidelity to these sites (Dobkin et al. 1995).
