From the |Natural History of Canadian Mammals.

“Arctic Foxes are the only foxes in Arctic Habitats, but along the southern boundary of their range they may overlap with Red Foxes”

“Red Foxes are thought to be such significant predators of Arctic Foxes that the southern limits of Arctic Fox distribution is largely determined by interspecific competition and predation by Red Foxes. In Europe, where Red Foxes are extending their range northwards, Arctic Foxes are becoming increasingly endangered on the mainland.”

“Red Fox in Canada occur north to the edge of the mainland and have gradually island hopped since 1918 from Ungava Peninsula to Baffin Island and from there to Bylot, Devon, Somerset,Cornwallis, and southern Ellesmere Islands.”