Does Abundant Wild Prey Decrease the Risk of Wolf Damages in Sheep Farms in Finland?

Wild ungulates are the main prey of wolves in Finland. In theory, abundant wild ungulate populations could reduce the need for wolves (Canis lupus) to prey on livestock, as well as attract predators to the area. We tested the prey scarcity hypothesis by examining whether the number of sheep depredation cases in Finnish wolf territories was related to the population densities of moose (Alces alces), white-tailed deer (Odocoileus virginianus), roe deer (Capreolus capreolus), or to the combined density of these ungulates. The absolute number of sheep depredation cases increased with the number of sheep farms, but was independent of the size of the wolf territories. Our statistical models suggested that the number of wolf attacks on sheep was negatively correlated with moose density, and also to some degree with roe deer density. White-tailed deer density and ungulate biomass did not explain numbers of wolf predatory attacks. The observed patterns could be explained by differences in the use of space by wild ungulates in relation to human settlements and sheep farms associated with those settlements; as in Finland, moose is the only ungulate that has been found to avoid human settlements.