BREEDING CAPACITY OF FEMALE BRUSHTAIL POSSUMS TRICHOSURUS-VULPECULA IN CAPTIVITY

This study records baseline data on the reproductive capacity of female brushtail possums (Trichosurus vulpecula) at Rangiora (near Christ-church) and compares the breeding season of captive and free-living possums. Repeat breeding was stimulated in captive females by removal of pouch young soon after birth. Captive females that bred, produced pouch young from March to October (more or less continuously), and some females produced four pouch young in one season. Free-living possums around Rangiora had two distinct periods of birth, in autumn (April/May/June) and spring (October/November). Reproduction ceased earlier in the year in captive possums than in possums in the wild, perhaps because of the stress of captivity. The probability of a given possum producing pouch young, and the number of pouch young produced, was not influenced by year, pelage colour, or the number of males in the breeding group. Weight was important: possums heavier than 3 kg were more likely to produce at least one pouch young and they produced more pouch young than possums <3 kg. Body weight, year, colour, and the number of males in the breeding group did not influence the time taken from introduction to the pen to birth of the first pouch young, or the interval between the first and second pouch young. Although fewer pouch young were produced in the second half of the season, the proportion of females giving birth to a second pouch young was not influenced by the month in which the first pouch young was removed. The poor productivity of this South Island colony compared with one in the North Island could be the result of the harsher climate and the southerly latitude.