These energetic lagomorphs spend the brief mountain summer gathering mixed greens, dashing about frenetically, then pausing to cast a wary eye around before scrambling off for another load. The plant material they collect is spread on rocks to dry. It's later stacked in rock crevices for storage. Bats come out when people go in. These small mammals eat more insects by body weight than any other predator, snatching their prey on the wing.
Bats roost upside-down in large groups, sleeping all day and hibernating all winter.
Some large species native to the Cascades migrate south in the coldest months. Mother bats nurse their young constantly in the first few weeks after birth, when they seldom leave their upside-down perch inside tree cavities or caves, even to feed. Old-growth forest, with snags, tree cavities and loose bark offer important roosting and nesting habitat for bats in the Cascades. Bats have extremely sensitive hearing. To keep warm, weasels need to eat approximately 40 percent of their body weight every day, more during cold winter months.