Wolf predation on moose and roe deer: chase distances and outcome of encounters

We examined chase distances of gray wolves Canis lupus Linnaeus, 1758 hunting moose Alces alces and roe deer Capreolus capreolus, and recorded details of encounters between wolves and prey on the Scandinavian Peninsula, 1997-2003. In total, 252 wolf attacks on moose and 64 attacks on roe deer were registered during 4200 km of snow tracking in 28 wolf territories. Average chase distances were 76 in for moose and 237 in for roe deer, a difference likely due to variation in body size and vigilance between prey species. A model including prey species, outcome of the attack, and snow depth explained 15-19% of the variation found in chase distances, with shorter chase distances associated with greater snow depth and with successful attacks on moose but not on roe deer. Wolf hunting success did not differ between prey species (moose 43%, roe deer 47%) but in 11% of the wolf attacks on moose at least one moose was injured but not killed, whereas no injured roe deer survived. Compared with most North American wolf studies chase distances were shorter, hunting success was greater, and fewer moose made a stand when attacked by wolves in our study. Differences in wolf encounters with moose and roe deer likely result from different anti-predator behaviour and predator-prey history between prey species.