Oestrous cycle of the common wombat, Vombatus ursinus in Victoria, Australia

Wild-caught female common wombats from Victoria, Australia, were studied in captivity to investigate the oestrous cycle by assessing vaginal cytology and peripheral plasma progesterone concentrations. Eight wombats, five adults (21-29 kg) and three subadults (19-23 kg), which were held for between 2 weeks and 11 months did not cycle in captivity. Their progesterone concentrations were consistently low (≤6.9 nmol L-1) and vaginal smears contained predominantly superficial epithelial cells. Three wombats (21-27 kg), held in captivity for > 1 year, regularly cycled (when bodyweights exceeded 23.5 kg). Information gathered from four consecutive cycles in each of these three wombats revealed a follicular phase with low progesterone concentrations (≤6.9 nmol L-1) and vaginal smears with a high percentage of superficial epithelial cells alternating with periods of high progesterone concentrations (range 41.6-123.8 nmol L-1) and smears in which parabasal-intermediate epithelial cells predominated. The average length of the monitored oestrous cycles was 47.2 days (35-60 days). The follicular phase lasted ~19 days and the luteal phase lasted ~28 days. In conclusion, wombats can cycle regularly in captivity even under conditions of intensive monitoring