The flying mammal that often hibernates in caves during cold months is the bat. In temperate regions, many insect-eating bats retreat to caves or mines, where stable temperatures protect them while winter insects are unavailable.
During hibernation, a bat enters torpor: its body temperature, heart rate, breathing, and metabolism drop dramatically. It survives largely on fat stored before winter. Bats may remain dormant for long periods, although occasional arousals can occur and consume valuable energy reserves.
Not every bat hibernates, and caves are not the only winter refuge. Some species migrate to warmer regions, while many tropical bats remain active year-round. Flying squirrels are gliding rodents rather than flying mammals, and birds and insects belong to entirely different animal groups. Cave-hibernating bats are also vulnerable to disturbance and diseases such as white-nose syndrome, which has caused severe declines in North American populations.