Maternal Care and Postnatal Development in the Japanese Long-fingered Bat, Miniopterus Schreibersi fuliginosus

Abstract

Lactation and growth of young in Minioptorus schreibersi fuliginosus were investigated during 1981-1984, together with an experiment in captivity. Adult females arrived at Nakadake-do Cave from May to June to form a maternity colony of up to ca. 4, 500 bats consisting almost entirely of pregnant females. Lactating females retrieved and suckled their own young, but would not accept alien ones. Almost all mothers, except ones shortly after parturition, nursed their young only during the daytime. In the first half of lactation period, there were two peaks of nursing: the first one during the forenoon and the second one during the midafternoon; but in the latter half only the former occurred. The young formed a huge, dense cluster, and its function was to heighten their body temperatures and growth rate. At the time of weaning, the body weight of young transiently decreased, although the forearm length almost reached the adult size at 6-7 weeks of age. Such a lightening resulted in the reduction of the young wing loading. Preweaning mortality was estimated at ca. 9 % for M. s. fuliginosus. The adult females left the nursery colony in early September, and then the remaining young emigrated somewhere.