Obligatory sperm storage in the skink Hemiergis peronii.

Female Hemiergis peronii ovulate in the spring; males' testes are small and without sperm in the spring, enlarge to a maximum in late summer, and decrease in the winter. Females' oviducts contain sperm over the winter. It follows that females are inseminated in autumn and store sperm until they ovulate in spring.