Moose (Alces alces) survival in three populations in northern Norway

Abstract

We used radio-collared individuals to examine the seasonal, annual, and regional variation in age-specific survival of moose (Alces alces) in three populations (Vega, Beiarn, and Troms) in northern Norway. In the two populations subject to a regular hunt, the annual mortality from hunting was higher, on average, than that from natural mortality for adult cows. In these study areas, the hunting mortality rate was higher for calves than for cows. For both age groups there was significant annual variation in hunting mortality, which was associated with differences in quota size among years. The survival rate of adult cows was high outside the hunting season (96%). There was seasonal variation in survival among calves, the highest significant mortality being found among neonates during summer in Vega and Troms and significantly higher mortality being found during winter in Beiarn. The natural mortality of calves differed significantly among regions during both summer and winter. The combined effects of density dependence, changes in age structure, and environmental stochasticity may explain this variation in calf-survival rate. In contrast, no significant seasonal or regional variation occurred in the survival rate of adult females.