Demography of a recovering wolf population in the Yukon

Abstract

We studied the dynamics of a wolf (Canis lupus) population recovering from intensive reduction in the Finlayson Lake area, Yukon, Canada. Within 6 years, numbers increased from 29 wolves, then stabilized at 245. The colonization of vacant territories by young wolf pairs was the primary mechanism of early population recovery. Reproduction and a low dispersal rate increased pack size in later years, and pack splitting allowed dispersing wolves to remain near natal packs. The rate of increase in the wolf population was density-dependent and related to wolf density, but was also related to the dispersal rate. The dispersal rate was density-independent and related to mean pack size and prey biomass : wolf index. The survival rate was age-dependent and not related to wolf density. In the early years of recovery, the rate of increase was supported by high survival rates and low dispersal rates. In later years, dispersal rates increased, stabilizing mean pack size and wolf density. Wolf density stabilized at levels predicted by the prey supply, but whether the wolf population is regulated by the availability of prey resources remains unresolved. Wolf density, pack density, and mean pack size were similar in 1983 and 1996, despite a 2- to 3-fold difference in prey biomass. We suggest that the interaction of wolf density and mean pack size in stable prey systems needs to be studied to determine the roles played by food supply and wolf social behavior in regulating wolf abundance.