Age-specific, Deterministic Model of Predator-Prey Populations: Application to Isle Royale

A deterministic model is proposed for the description of predator-prey systems in which the prey has an age-specific vulnerability to predation. The model is developed on the basis of observations of the moose and wolf populations of Isle Royale, Michigan. The moose are divided into three groups, the very young, the adults, and the very old or sick. The three groups have different vulnerability to predation by a single population of wolves. The model incorporates a saturation effect for the moose population and a satiation effect for the wolf population. It appears to reproduce quite well the almost monotonic trend toward equilibrium observed since the arrival of wolves on the island.