Summer activity of Myotis lucifugus (Chiroptera:Vespertilionidae) at hibernacula in Ontario and Quebec

Abstract

"Swarming" refers to the summer nocturnal flights through hibernacula by the five species of bats known to hibernate locally. A total of 6400 bats was handled during studies of swarming at 10 hibernacula in Ontario and Quebec from 1966 to 1968. Juveniles comprised over 50% of the swarming population, and the proportion of females in this population was greater than that observed in hibernating populations. Two phases of swarming have been distinguished: the first, occurring in August, lacks both sexual activity and a hibernating population, and the second, which begins in September, involves both sexual activity and the buildup of a hibernating population. Possible functions of swarming are discussed.