The little brown myotis is abundant in Wind Cave National Park and throughout forested areas of the U.S. as far north as Alaska. In the West it is found mainly in mountainous and riparian areas in a wide variety of forest habitats; from tree-lined xeric-scrub to aspen meadows and Pacific Northwest coniferous rain forests. This species is especially associated with humans, often forming nursery colonies containing hundreds, sometimes thousands of individuals in buildings, attics, and other man-made structures. The little brown myotis is poorly studied in the West. In northern Arizona, numerous nursery colonies of 50-100 bats each have been documented beneath exfoliating bark on ponderosa pine snags. In addition to day roosts in tree cavities and crevices, little brown myotis seem quite dependent upon roosts, which provide safe havens from predators that are close to foraging grounds. Unlike their eastern counterparts, the winter habitats of western little brown myotis remain a mystery. Despite summer nursery colonies numbering in excess of 1,000 individuals, only a handful of hibernating individuals have ever been found. In the West, where few caves or mines contain appropriate temperature or humidity for hibernation, these bats may hibernate in hollow tree cavities in moist coastal areas or in deep cliff-face crevices. Little brown myotis forage over water where their diet consists of aquatic insects, mainly midges, mosquitoes, mayflies, and caddisflies. They also feed over forest trails, cliff faces, meadows, and farmland where they consume a wide variety of insects, from moths and beetles to crane flies. Individuals can catch up to 1,200 insects in just one hour during peak feeding activity.
For information about white-nose syndrome (WNS) and Wind Cave National Park click here.