POPULATION DYNAMICS AND YIELD OF A MOOSE POPULATION WITHOUT PREDATORS

Abstract

Population dynamics, potential rate of increase (r_p), and potential yield of a moose population with no predators in south-central Sweden during 1980 through 1988 are described. Except for 2-year-old females (0.50 calf/female), age-specific natal rates were high and stable between age classes (x̄=1.17 calves/female for females > 3 yrs. High natality rates in combination with low annual non-hunting death rates (calves=1%; adults=5.6%), and negligible dispersal rates (<1%) yielded a potential rate of increase (r_p) in the Grismö moose population of 0.40. Consequently, 50% of the winter population could potentially be harvested each autumn if the population was maintained at the same density. With a winter density of 1.3 moose/km², a high annual yield was achieved in terms of meat (75 kg/km²) and number of animals killed (0.65 moose/km²). Under these circumstances hunting pressure must be high and male biased. The risk of dying (mainly through hunting) before numeral 5 years of age was >90% among bulls and 70% among females. Selective harvesting on low-productive females in conjunction with high hunting pressure on bulls may further enhance the annual potential rate of increase to at least 60% of winter population. In other areas in southern Sweden the potential rate of increase may even exceed this rate by higher age specific natality.