Studies of Macropodidae in Queensland. 3. Reproduction in the grey kangaroo (Macropus major) in Southern Queensland

Abstract

Reproduction in the grey kangaroo has been studied in captivity and in two field populations. In captive animals, the oestrous cycle ranged from 41 to 43 days and the gestation period from 35 to 38 days. Pouch life of the young averaged 297 days; the interval between successive births, in the absence of a delayed embryo, averaged 356 days. Delayed embryos in captive females were produced at an oestrus occurring between 112 and 243 days after a birth; the delayed birth normally occurred when the first pouch young was between 291 and 312 days old. Female kangaroos in the field commenced reproductive activity at ages ranging from 17 to 28 months, with reduced fertility in old age (over 16 years). Delayed embryos were seldom found in field-collected kangaroos and only in those with pouch young older than 174 days. No defined breeding season was apparent, though more young were conceived during October-December than at other times. Approximately 50% of young failed to reach independence. Young suckled until 18 months of age both in captivity and in the field. Males were observed to be reproductively effective between the ages of 3 and 15 years.