Night-Roost Usage and Nocturnal Behavior in the Japanese House-Dwelling Bat,Pipistrellus abramus

Night-roost usage and nocturnal behavior in Pipistrellus abramus were examined in the school buildings in Kagoshima Prefecture. Night-roosts were used from May to October, with their peak in August. The bats began to use night-roosts at about 80 min after sunset, and left the roosts at about 70 min before sunrise. Solitary roosts were almost exclusively occupied by males, while colonies at the night-roosts consisted of females and/or young, and attained the maximal size of 30 bats in August. The night-roosts were warmer than ambient at night, and firstly provided sites for resting between feeding bouts, promoting digestion of food or absorption of nourishment. The duration of roosting bouts at night varied from 0.5 to 7.6 hrs, and became longer in September. Adult females and males occupied different night-roosts in general. Females of P. abramus were faithful to particular night-roosts, while males did not defend night-roosts, and frequently changed their roosts. Copulation did not occur at the night-roosts.