Open access publications in the SLU publication database

Abstract

Apex predators may have both direct and indirect effects on other species through predation and competition. I investigated the effects of wolves (Canis lupus) on prey species, competitors (including humans) and the scavenging guild after the re-colonization by wolves of the Scandinavian Peninsula. Field methods included telemetry, snow-tracking, age determination, and camera monitoring.

Human extermination of wolves at the end of the 19th century in combination with the extent and mode of hunter harvest has caused moose (Alces alces) to become predator-naïve. This has resulted in high hunting success rates and short chase distances by wolves hunting moose, compared to areas in North America where moose have been continuously exposed to wolf predation. The high kill rate by wolves on moose, in combination with mainly additive wolf predation resulted in exploitation competition between wolves and hunters, leading to reduced hunter harvest of moose within wolf territories. In contrast, neither exploitation competition nor interference competition were evident between wolves and Eurasian lynx (Lynx lynx), which was most likely a result of wolves and lynx having different main prey species, a high density of the shared prey species and low densities of both predator species.

The largest food source for scavenging species regarding the annual amount of available biomass was remains after hunter harvest of moose in autumn. Presence of wolves slightly reduced available biomass to scavenging species, but more important, wolves reduced the high seasonal variation of available biomass by providing carcasses all year round. The red fox (Vulpes vulpes), common raven (Corvus corax), European pine marten (Martes martes), and northern goshawk (Accipiter gentilis) may benefit from the return of wolves, due to their high utilization of wolf-killed moose in spring when the presence of wolves increased the availability of carcasses.

In summary, apex predators will have relatively little influence on other species in areas where human activities have a large impact on animal densities, such as in the wolf and moose system on the Scandinavian Peninsula.