Wolverines and their prey in southern Norway

Abstract

Wolverines (Gulo gulo) recolonized the Snohetta plateau in southern Norway in 1976-1979 after an absence of over 50 years. This is presently the southernmost part of the wolverine's distribution and the only area where it coexists with wild reindeer (Rangifer tarandus) in western Europe. Other, larger predators in the Scandinavian ecosystem, the wolf (Canis lupus), lynx (Lynx lynx), and brown bear (Ursus arctos), have been absent from the area since the beginning of this century. We monitored wolverine numbers, reproduction, and diet during the denning period and studied the effects of abundance of different prey species on wolverine reproduction. Although there were differences in productivity among maternity dens, the main factor influencing the number of wolverine cubs surviving was the abundance of small rodents (p = 0.0002). Although small rodents constituted the main factor explaining variation in cub numbers, the basic prey during the denning period was reindeer. Hares (Lepus timidus) accounted for a significant but stable part of the diet during the denning period. The wolverine was an important predator on sheep (Ovis aries), but we found no evidence that sheep are an essential part of its diet.