Habitat
These bats occur primarily at middle elevations in desert, riparian, grassland, and woodland habitats, but they have been recorded at 2,850 meters in spruce-fir habitat in New Mexico, and at low elevations along the Pacific Coast (Barbour and Davis 1969, O'Farrell and Studier 1980, Hoffmeister 1986, Armstrong et al. 1994, Oliver 2000, Foresman 2001, Ammerman et al. 2012). Roosts are in caves, mines, cliff faces, rock crevices, old buildings, bridges, snags, and other sheltered sites (Barbour and Davis 1969, Rabe et al. 1998, Cryan et al. 2001, Foresman 2001, Weller and Zabel 2001, Lacki and Baker 2007, Hayes 2011). In South Dakota, the bats roosted in rock crevices and often changed roosts to nearby locations; maternity colonies maintained group integrity through roost changes, and females carried nonvolant young with them through roost changes (Cryan et al. 2001). In spring and summer in northern California, the bats roosted in snags in early to medium stages of decay and switched roosts often (Weller and Zabel 2001). Rabe et al. (1998) documented roosting in ponderosa pine snags in northern Arizona. On the east side of the Cascade Range in Oregon and Washington, females roosts primarily in rock crevices, infrequently in ponderosa pine snags; roost changes to nearby sites were frequent (Lacki and Baker 2007). In Colorado, most maternity roosts were in crevices of rock faces, sometimes in abandoned mines or in an abandoned cabin; roost changes were infrequent (Hayes 2011). In spring and summer, males roost separately and rarely are found in nursery colonies (Nagorsen and Brigham 1993). Winter habits are poorly known; hibernacula include caves, mines, and buildings (Western Bat Working Group species account, 2005).
Reproduction
Ovulation, fertilization, and implantation occur in spring (O'Farrell, in Wilson and Ruff 1999). Gestation lasts 50-60 days. Births occur from mid-May to mid-July, with substantial variation among regions and within particular colonies (O'Farrell and Studier 1973, Ammerman et al. 2012). Litter size is 1. Young can fly at 16-17 days. Colony size ranges up to several hundred; colonies begin to disperse by October.