Intrinsic Rate of Increase for a Brushtail Possum Population in Rata Kamahi Forest, Westland

An estimate of intrinsic rate of increase (r(m)) of a brushtail possum (Trichosurus vulpecula) population was calculated from the measured increase in possum numbers after a poisoning operation in Westland rata/kamahi forest. Our empirical estimate of r(m) (0.22—0.25) was lower than published estimates for this species (0.30, 0.34, 0.59). Consequently, the control operation was effective for longer than predicted by population models that used these published values. We suggest reasons why the rates of fecundity and juvenile survival used in other modelling studies may have been inappropriate for this population.