The population increased from 10 individuals in 1953 to 116 animals in 2001 (Fig. 1). The stochastic growth rate in this population was s = 0•0511 ± 0•0177 (SD) with environmental variance 2e2 = 0•0159 ± 0•004. According to eqn 2a, the deterministic growth rate was then r = 0•0591.