Modelling territoriality and wolf–deer interactions

Abstract

WE propose here a mechanism for territorial pattern formation in wolves (Canis lupus) and analyse it using a spatially explicit mathematical model incorporating wolf movement and scent marking. Model results reflect field observations from northeastern Minnesota: buffer zones where wolves are scarce arise between adjacent packs, and near these buffer zones there are increased levels of scent marking^1,2. Territories are arranged in a spatial mosaic (Fig. 1) which covers the wolf range. In the model formulation no assumptions are made about actual existence or extent of wolf territory and buffer zones; these arise naturally as stable steady-state solutions to the equations. We show mathematically how reduced predation by wolves in the buffer zones provides a refuge for prey species. Field studies support this; distribution of a primary prey species, white-tailed deer (Odocoileus virginianus), correlates negatively with that of wolves. Deer are found primarily in buffer zones^3,4 (Fig. 2).