THE MATING SYSTEM OF PIPISTRELLUS-KUHLI (MICROCHIROPTERA) IN ISRAEL

The mating system of the microchiropteran bat Pipistrellus kuhli, was studied in kibbutz Sde Eliyahu, Israel. These bats roost during the day under roofs and in wooden huts and attics and hunt in uncluttered environments (e.g., fields) to which they fly along permanent routes. From the beginning of March the females aggregate, in hundreds, at maternity colonies. Pregnant females are found between March-May and lactating females from May-July. Maximal body weight is reached in autumn (October-November) before hibernation, and in spring, due to pregnancy. Two types of males were observed : those which roost singly all year round in permanent places located along the females' flying routes, and those which roost in small groups (7-16 individuals), which are located elsewhere. Single males are characterized by attaining maximal body weight in March and minimal body weight in October, having larger testes and exhibiting songflight and false landing displays. In contrast, the body weight of grouped males fluctuates like that of the females. They have much smaller testes and do not exhibit mating displays. It is concluded that the system of P. kuhli might be categorized as female resource polygamy, where females are highly social and travel over a large area but along permanent routes, and the reproductive males roost and court along these routes.