Growth-Rates of the Bandicoot Isoodon-Macrourus and the Brushtail Possum Trichosurus-Vulpecula

Abstract

Although the bandicoot Isoodon macrourus and the brushtail possum Trichosurus vulpecula give birth to similar-size young, about 200 mg, the pouch young of the bandicoot grow more quickly than those of the possum. The bandicoot is weaned at 59 days when the body weight is between 90 and 250 g. A young possum weighs about 20 g at Day 60 and between 780 and 1031 g when weaned at Day 170-180 post partum. The body weight of both species has been described previously as a continuous curve expressed by a quadratic equation. In this study, instead of assuming the growth curve to be continuous, the growth curve has been expressed as two components. The growth rates of both species were similar from birth until Day 12 post partum; the bandicoot then had a faster growth rate. The results from iterative analysis indicated a change in growth rate at Day 30 (data for Days 31 and 32 were missing) and Day 96 post partum for the bandicoot and possum, respectively. Thus, both marsupials showed a change in growth rate as hair appeared, eyes opened and the young first left the pouch.