Resource‐Related Interactions Between Wolverines and Brown Bears in Scandinavia

Ongoing recovery of large carnivore species into their former ranges increases the occurrence of interactions among them. The recovering Scandinavian wolverine ( Gulo gulo ) population has recently expanded southwards and is increasingly overlapping with the core of the brown bear ( Ursus arctos ) range. Both species are facultative scavengers that feed on moose ( Alces alces ) carcasses, which are an important resource all year round for wolverines and seasonally for bears. Reliance on the same resource may lead to interactions. We monitored five GPS‐collared wolverines in central Sweden to investigate feeding sites with food remains and determine bear activity. In addition, we used motion‐triggered cameras to monitor wolverine and bear activity at three wolverine rendezvous sites (i.e., temporary sites where females keep cubs) and at a recently bear‐killed adult moose carcass. We found 115 wolverine feeding sites, of which 25 (22%) showed signs of bear activity. At 24 sites we found remains from adult moose carcasses, five presumably bear‐killed of which two were fresh (< 1 week). Based on GPS‐data, wolverines repeatedly used these recently bear‐killed moose for periods ranging from a few hours to multiple days. Bear activity was documented at two of the three presumed rendezvous sites used by a female wolverine with cubs. Camera data also documented repeated visits by at least three different wolverines at the presumed bear‐killed moose carcass, including visits short before and after bear activity at the site. Our results illustrate that wolverines and bears overlap and share food resources, potentially leading to direct and/or indirect interactions. These observations suggest that co‐occurrence between these two species create both feeding opportunities and potential risks for wolverines, which deserves further research.