THE OWLS ODYSSEY - A CONTINUOUS MODEL FOR THE DISPERSAL OF TERRITORIAL SPECIES

In this paper, a composite model is developed that consists of a continuous model for dispersal set within a difference equation model for the life history of territorial species. Two dispersal models are considered: one that assumes that suitable habitat is uniformly or randomly distributed throughout the range of the population, and one that assumes that home ranges are concentrated in clusters of suitable habitat. These models explicitly consider the cost of dispersal by including ongoing rates of mortality due to predation and starvation while individuals search for a territory. The cluster model also differentiates between mortality within and outside of clusters. An analysis of the difference equation model demonstrates a threshold for density of suitable habitat below which the population must decrease to extinction, and above which the population tends monotonically to a stable positive equilibrium size. In addition, it is established that the equilibrium size of the population can be increased by consolidating the reserves of suitable habitat into larger clusters.