LIFE-HISTORY AND ROOST SWITCHING IN 6 SUMMER COLONIES OF EASTERN PIPISTRELLES IN BUILDINGS

Summer colonies of the eastern pipistrelle, Pipistrellus subflavus, in six different buildings in Indiana were studied by the owners of the buildings. Colonies generally started forming from 13 to 29 April. Siz e of the colony increased gradually and reached a maximum of 7 to 29 a dults ((X) over bar = 15 +/- 7 SD, n = 18) from 26 April to 7 June. Bi rths occurred from 30 May to 11 July, but most young were born from 12 June to 1 July. Juveniles apparently became volant ca. 4 weeks of age : and foraged with their mothers for ca. 1 week. Adults often abandone d maternity roosts soon after weaning, but young remained longer. Ther e was considerable daily variation in the number of bats in a given co lony, and sometimes the entire colony disappeared, even when flightles s young were present, suggesting that each colony was using more than one roost.