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 Wolfkilled 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.