Surface activity and structure of a hydrothermally-heated maternity colony of the Little Brown Bat, Myotis lucifugus, in Alaska

In north-temperate environments reproductive bats require access to warm, sheltered roosts to raise young successfully. In Southeast Alaska cool temperatures and persistent rain and fog may limit the availability of suitable natural maternity roosts. Heated man-made structures provide shelter for most known bat nurseries. We describe the structure, thermal environment, and surface activity of the first documented non-commensal maternity colony of Myotis lucifugus in Alaska. This colony of over 450 bats is uniquely located at a hydrothermally-heated roost beneath coastal beach boulders on Chichagof island in Southeast Alaska. The importance of hydrothermal refuges in determining bat distribution in this region is discussed.