Annual reproductive cycle and annual cycles of reproductive hormones in plasma of female Niveoscincus metallicus (Scincidae) from Tasmania

Niveoscincus metallicus is a small viviparous skink common in Tasmania. We describe the annual reproductive cycle of female N. metallicus and relate this to changes in plasma levels of progesterone and estradiol. Vitellogenesis begins in autumn (March), with first matings in April, prior to entering winter torpor. Ovulation occurs in mid-September about two weeks after spring emergence. Size adjusted atresia of vitellogenic follicles was 8% in the population studied. No loss of embryos in utero was observed and young are born in January. Plasma estradiol levels are significantly elevated during the preovulatory phase. Progesterone concentrations are low through most of the year but rise during gestation and are highest during the second trimester, declining well before parturition.