Effect of changing from a short-day to long-day photoperiod on the breeding season of the brushtail possum (Trichosurus vulpecula).

In Queensland, possums (Trichosurus vulpecula) in the wild and in captivity first give birth during March and April and continue to give birth throughout the year until November. The possum has a gestation length of 17.5 days, gives birth to one young, and lactation continues for approximately 180 days. If the newborn possum is removed during the breeding season, the possum will ovulate approximately 9 days later and give birth approximately 26 days after removal of the pouch young (RPY). Repeated RPY may be used to determine the duration of the breeding season. In this study, the effect on the breeding season of a marked change in photoperiod From a short-day to a long-day was examined by comparing three groups of possums in different photoperiods for 13 months. One group of five female and two mail possums (group A) was housed in a natural photoperiod and a second group (B) was housed in a short-day photoperiod (10 h light: 14 h dark) throughout the study. The third group (C) was housed in a short-day photoperiod until each possum gave birth, the pouch young was removed, and the possum transferred to a long-day photoperiod room (14 h light: 10 h dark) for the remainder of the study. The possums held in a natural photoperiod, group A, gave birth to a total of 27 births in the one breeding season from March to October.(ABSTRACT TRUNCATED AT 250 WORDS)