Interspecific Killing of Vulpes vulpes (Red Fox) Kits at a Den Site by Canis lupus (Gray Wolf) in Isle Royale National Park, Michigan

Canis lupus (Gray Wolf or Wolf) have killed subordinate canids that scavenge on Wolf-killed prey, but little evidence is available for antagonistic behavior of Wolves toward other canids at interspecific den sites. We investigated clusters of locations from a global positioning system (GPS)-collared male Wolf, translocated to Isle Royale National Park, MI, on 23 March 2019. On 17 May 2019, we investigated a GPS cluster of the Wolf and observed 3 Vulpes vulpes (Red Fox) kit carcasses at an excavated Red Fox den site. We report details from this event and evidence for interspecific aggression and implications for Wolf-Red Fox interactions. To our knowledge, this represents the first reported killing of Red Fox kits at their den by a Wolf. Limited reports of interspecific killings by Wolves of Red Foxes suggests this interaction was opportunistic and rare.