Habitat
Habitat is primarily wooded areas (e.g., ponderosa pine, pinyon-juniper, pine-oak, Mexican woodland, oak brush) in mountains and canyons but also includes riparian (e.g., cottonwood, willow, tamarisk) woodland or tall shrubland, desert scrub, and open arid habitats (Cockrum and Musgrove 1964, Barbour and Davis 1969, Czaplewski 1983, Hoffmeister 1986, Rabe et al. 1998, Oliver 2000, Adams 2003, Brown and Berry 2004); habitat ranges from Mohave desert scrub of low desert ranges to white fir forest (Hoffmeister 1986). These bats often roost in rock crevices, caves, and mines, and so they are often found near cliffs, rocky slopes, and lava flows (Adams 2003). They are frequently netted along streams or over ponds.
Maternity colonies of 30 to 150 individuals have been found in mine shafts, boulder piles, sandstone crevices, lava beds, and beneath the loose bark of large ponderosa pine snags (Cockrum and Musgrove 1964, Czaplewski 1983, Rabe et al. 1998, Morrell et al. 1999, Adams 2003). In southern Utah, maternity roosts used by at least 15 individuals were in three cracks of the same cliff face; the roosts were on a large northwest-facing cliff, in the eastern side of a small box-canyon, with piñon-juniper woodland on ridge tops and bottoms of canyons (elevation ca. 1,800 m); roosts were in the top one-half of the cliff face, which was tall and highly fractured, with a large talus slope at the base (Siders and Jolley 2009). In northern Arizona, most maternity colonies were under sloughing bark of large-diameter ponderosa pine snags (Solevsky and Chambers 2009). Bachelor roosts were in vertical sandstone cliff faces in piñon-juniper woodlands. Of 11 maternity roosts in snags located in 1993-1995, only one continued to function as a roost in 2006-2007 (Solevsky and Chambers 2009).
Hibernating individuals have been found in a cave in an area of pinyon-juniper woodland in northern Arizona (Hoffmeister 1986), but in general winter ecology is poorly known.
Reproduction
In New Mexico, Arizona, and Durango, pregnant females bearing a single embryo have been collected in June. In Arizona, young are born in mid to late June and are volant by late July (Barbour and Davis 1969, Hoffmeister 1986). Lactating females have been found from the second week of June to the first week of August (Czaplewski 1983). Sexual segregation apparently occurs during the maternity season (Rabe et al. 1998, Solevsky and Chambers 2009).