Natal den prey delivery of Arctic and red fox in relation to landscape patterns in food availability

Arctic fox (Vulpes lagopus) and red fox (Vulpes vulpes) may compete for resources in areas of sympatry, with diets varying according to fluctuations in small mammal abundance and the availability of alternative prey. We investigated how spatial and seasonal prey availability influences fox prey utilization during the denning period using motion‑activated cameras at natal dens (2018 - 2025) near the south coast of Hudson Bay, Canada. Camera data were used to identify fox species, reproductive activity, and prey delivered to dens. Arctic fox diets were dominated by geese (83%; adults, eggs, and goslings), whereas red fox primarily delivered small mammals, mainly rodents (52%), as well as red squirrels (Tamiasciurus hudsonicus) and snowshoe hares (Lepus americanus). Greater goose use by Arctic fox corresponded with both spatial variation and the temporal overlap of fox and goose breeding, maximizing egg and gosling availability. Goose delivery by both species increased with goose density. These results indicate that reproductive timing and spatial factors shape prey selection, supporting the resource tracking hypothesis whereby foxes align energetic demands with peak prey availability.