Selection of summer roosting sites by Indiana bats (Myotis sodalis) in Missouri

Summer roosting sites were studied at four maternity colonies of Indiana bats (Myotis sodalis) in northern Missouri. Colonies of Indiana bats used two types of roosts, primary and alternate, that differed in intensity of use, number, and probable function. Primary roosts were denned as roosts where use by >30 bats on more than one occasion was observed. The number of primary roosts per colony ranged from one to three. All primary roosts were in standing dead trees situated in trees exposed to direct sunlight. Alternate roosts were used by smaller numbers of bats. These roosts included both living and dead trees that typically were located within the shaded forest interior. Differences in patterns of use between types of roosts seemed to be influenced by weather conditions in that use of alternate roost trees increased during periods of elevated temperature and precipitation. Indiana bats have specific requirements for roost sites, but also must be able to relocate when loss of bark, tree fall, or other events render their current roost sites unusable. Practices of forest management within the summer range of Indiana bats should favor retention of large-diameter, mature, and senescent trees.