George Stimpson

Some species of tree-dwelling bats in the North Temperate Zone are known to migrate, as birds do, going south in the winter when insects are unavailable and returning north in the spring. Other species hibernate, that is, they hang head downward (sometimes in great clusters) in a semitorpid state in caves, crevices, hollow trees, buildings and other retreats during the cold season when they cannot obtain food. Occasionally hibernating bats become active and emerge from their retreats during warm spells. Among the bats of the United States and Canada that are believed to be migratory are the common little brown bat, the red bat, the hoary bat and the spotted or jackass bat. Apparently the red bat migrates from the northern part of its range and then hibernates in the southern part. It is believed that in migrating the male and female bats By in separate flocks. As a rule bats become fat as the cold season approaches. Bats in the tropics remain active the year around.