Reproduction and the female reproductive cycle of Nyctophilus geoffroyi and N-major (Chiroptera: Vespertilionidae) from south-western Australia

The reproductive cycles of female Nyctophilus geoffroyi and N. major from south-western Australia are described from capture records and histological examination of tissue from fixed specimens. The sequence of reproductive events for both species was similar to that described for other vespertilionid bats from southwestern Australia. Mating commenced between March and May. Sperm were stored in the caudal isthmus of the oviduct and in endometrial glands near the utero-tubal junction. Ovulation and fertilisation occurred in late August or September and twinning was common. Parturition occurred between late October and November, with volant young first captured during December, but it appeared not all N. geoffroyi females were reproductively active every year. Lactation had generally ceased by February, which was when the last detectably juvenile bats were captured.