Wolf inter-territorial variation in prey use and selection in a multi-ungulate system

Sammanfattning

Grey wolves (Canis lupus), as generalists and opportunistic predators, are highly adaptable and have shown to thrive on a wide variety of prey species. The wolf population in Scandinavia has recently been expanding from prey systems dominated by moose (Alces alces) and roe deer (Capreolus capreolus) in central Scandinavia to more southern areas in Sweden where multiple ungulate species are potential prey. This study investigated the inter-territorial variation in feeding behaviour of wolves in pairs and packs across Sweden, using a new DNA-method for prey detection on 1564 wolf scat samples. Based on the frequency of occurrence of prey species in the scats, the diet of wolves was mainly dominated by large ungulates with moose as the main prey in central Sweden, and roe deer followed by moose in southern Sweden. Wolves expanded their diet by including a higher proportion of alternative ungulate species where their abundance increased towards the south. Comparing prey selection across wolf territories showed that moose was overall selected, roe deer was consumed proportional to its abundance and red deer (Cervus elaphus), fallow deer (Dama dama) and wild boar (Sus scrofa) were in general avoided, but with a large variation among territories. Wolves’ selection for moose was negatively influenced by high abundances of fallow deer, suggesting dietary shifts due to the presence of alternative prey species. These findings have management and conservation implications by showing how the presence of alternative ungulate species lowered the consumption and selection of the main prey, moose.