Feast to famine: Sympatric predators respond differently to seasonal prey scarcity on the low-Arctic tundra

Resource fluctuation is a major driver of animal movement, influencing strategic choices such as residency vs nomadism, or social dynamics. The Arctic tundra is characterized by strong seasonality: resources are abundant during the short summers but scarce in winters. Therefore, expansion of boreal-forest species onto the tundra raises questions on how they cope with winter-resource scarcity. We examined a recent incursion by red foxes (Vulpes vulpes) onto the coastal tundra of northern Manitoba, an area historically occupied by Arctic foxes (Vulpes lagopus) that lacks access to anthropogenic foods, and compared seasonal shifts in space use of the two species. We used 4 years of telemetry data following 8 red foxes and 11 Arctic foxes to test the hypothesis that the movement tactics of both species are primarily driven by temporal variability of resources. We also predicted that the harsh tundra conditions in winter would drive red foxes to disperse more often and maintain larger home r..., Capture and satellite telemetry. – Between 2017 and 2019, we captured 10 red foxes and 13 Arctic foxes using Tomahawk (Model 208, Tomahawk Live Trap Co., WI) and padded leghold traps (Softcatch # 1.5, Oneida Victor Ltd, USA). Traps were placed on active dens or by protruding features (e.g., driftwood or spruce islets) and remained open continuously for up to one week. We checked the traps every 4–6 hours and closed them during extreme weather conditions (e.g., blizzard or temperatures below -25°C). We captured adult foxes from March to May when snow still covered the ground and facilitated travel over large distances, except for two adult foxes caught near our field camps in June 2018. We did not anesthetize the foxes, which were easily handled without chemical restraint. Foxes were first wrapped in a blanket and released from the traps, then we assessed sex and body condition, deployed an Iridium satellite collar (#4170 or 4270, Telonics, Mesa, Arizona, USA; ~100g, i.e., 2–4% of a fox ...,