Open access publications in the SLU publication database

Abstract

As large carnivore populations are recovering in northern boreal ecosystems of Europe and North America, there is a need to understand how these changes in predator communities influence prey populations and ecosystems. Moreover, human-wildlife conflicts are frequently causing challenges where large carnivores coexist with humans, often due to predation on livestock. In Sweden the brown bear (Ursus arctos) distributional range largely overlaps with the reindeer (Rangifer tarandus tarandus) herding area, but knowledge of potential losses to bear predation has been scarce. Also, little information exists on the behavioral interactions between semi-domesticated reindeer and brown bears in Fennoscandia. In this thesis I present data from two forest reindeer herding districts in Northern Sweden, showing that brown bear predation on reindeer neonates can be considerable on forested calving grounds. Also, brown bear predation was very limited in time, concentrated to the first weeks following birth of the reindeer calves. Moreover, using GPS location data to compare brown bear and reindeer resource selection on the reindeer calving ground, indicated that brown bear behavioral adjustments to search for reindeer possibly dominate over antipredator responses by reindeer in terms of altered resource selection on a daily and seasonal basis. Nevertheless, a closer investigation of the spatial distributions of reindeer calf kill sites suggested that use of clear-cuts, higher elevations and areas closer to large roads may reduce risk of bear predation. However, even though clear-cuts may provide advantages for survival in the short term, logging may eventually yield negative effects for the reindeer, as abundance of young forest increase, which is a preferred habitat by brown bears. Finally, using data on reindeer movements and brown bear density from seven herding districts in Sweden I show that reindeer females experiencing higher risk of bear predation, deviate more from optimal foraging and increase movement rates, which may lead to lower body condition and, in turn, possible consequences for population dynamics.