Sex and reproductive class composition of solitary bats and roosting groups in Pipistrellus abramus

Abstract

Pipistrellus abramus is a house-dwelling bat, which is mainly distributed in the urban areas of Japan. Sex and reproductive class composition of solitary bats and roosting groups in this species were surveyed in Tokyo. Most solitary bats were found to be adult males. From May to early August, most of the roosting groups contained only adult females. From late August to September, most of the groups comprised adult females and juveniles. The number of bats in roosting groups containing mother bats was found to be 3–22. The number of adult males in a roosting group was less than 2, regardless of the group size. In adult females, some bats were recaptured at the same roost. On the other hand, the longest distance from the roost captured to the roost recaptured was 87 m.