Results
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.
Annual variations in the population growth rates were significantly related to autumn climate and winter climate between year t and t + 1. High growth rates were found in years with mild weather during the period September–November (b = 0•039, P = 0•001) and with little snow depth in May (b = −0•005, P = 0•008). The proportion of explained variance in σe2 was 9•7% and 1•1% for autumn temperature and May snow depth, respectively.