Nocturnal activity of the endangered Indiana bat (Myotis sodalis)

Acoustic monitoring and radio-tracking were used to study the nocturnal activity of adult female Indiana bats Myotis sodalis at a maternity site in Michigan, U.S.A. Pregnant bats did not use the day roost at night, but lactating females returned 2-4 times/night for 32 +/- 7 (SE) min/visit, presumably to feed their young. Both pregnant and lactating females night roosted as solitary individuals in trees within their foraging areas; night roosting occurred 0-6 times/night for 14 +/- 1 min each time. Bats foraged for most of the night, with the total duration of flight equalling 375 +/- 16 min/night. The bats used 13 different foraging areas that were located 0.5-4.2 kin from the day roost. Bats did not fly over open fields but travelled along wooded corridors, even though such behaviour increased commuting distance by 55 +/- 11%. Current models of habitat suitability for this endangered species should be modified, taking into account the use of wooded commuting corridors and the large home range of these bats.