Abstract
This study aimed to describe the nursery colony structure of the Japanese long-eared bat, Plecotus auritus sacrimontis. We investigated four colonies over five years by the banding-recapture method in Shizuoka and Yamanashi Prefectures, central Japan. We analyzed yearly changes in colony composition and size, sex ratio, roost fidelity and age of first pup-birth. Colonies were composed of 7–33 individuals, mainly mothers, immature females, and infants of both sexes, although a few adult males were also found in these colonies. The mean sex ratio (male:female ratio) of infants was 0.54, while that of adults was 0.01. Roost fidelity differed remarkably between males (3.6%) and females (54.5%). Most banded infant males did not return to their natal colony. On the other hand, return rates of banded infant females were 78.9%, 16.7%, 63.6% and 0%. Females had their first young when they were one or two years old.
