Reproductive Biology of Captive Wolverines

The reproductive biology of seven male and eight female wolverines (Gulo gulo) was studied. Testes of all males were fully regressed from August through January. Plasma levels of testosterone began to increase in January and were followed by an increase in testicular size, which reached near-maximal size in early April and peaked in June. Thereafter, plasma testosterone declined rapidly and testes were fully regressed by mid-August. All females were anestrus from September through April. Vaginal cornification increased in May and was accompanied by increased levels of estradiol. Maximal cornification of the vagina and vulval enlargement were achieved in June and July. Females for which vaginal cornification exceeded 80% were placed with males, but no copulatory activity was observed.