Newborn bats are covered with fine silvery-gray hair. This is the largest bat found in Idaho. Hoary bats usually roost at the edge of clearings preferring foliage of both coniferous and deciduous trees. Less common sites include cavities or, in unusual situations, caves or anthropomorphic structures. Grasshoppers, dragonflies, wasps, beetles, flies, and moths, apparently the preferred food, are eaten.
Hoary bats are most common in the southwest.
They roost individually in trees, usually at the end of branches where they often choose a site that is not visible from above. The area below the roost is open and likely is along the edge of a clearing. Jays appear to be significant predators on this species. Hoary bats may fly in waves from northern forests to southern latitudes, usually in the late fall. Spring return migrations do not appear to be organized, but more needs to be learned about the migratory pattern of this species.