ИСТИНА

Food distribution and predation pressure are usually considered as the main factors of spatial behavior. We examined range use of arctic fox, an apex predator on Bering Island (North Pacific). The study was conducted in July - August 2014 and 2016 near the northern fur seals rookery. Thereby in summertime these foxes had an extraordinary abundant source of food (seal placentas and carcasses). Nine adult foxes (4 males and 5 females) from 3 breeding (2014) and 4 non-breeding (2016) family groups were equipped with GPS-collars which collected fixes every 5 minutes. Foxes were tracked during 12–30 days each. Home range size (N=7, number of family groups) was (Mean±SD) 48±29 (min-max: 19–90) ha by 99.5% Brownian bridge movement model (BBMM), 39±28 (14–81) ha by 95% fixed kernel and 79±47 (29–144) ha by MCP100. Size positively correlated with the distance between home range activity centers and the most populated seal breeding site. The BBMM home range borders of males and females from the same mated pairs were nearly identical. For foxes from adjacent family groups HR overlap was 12±11 (1–38) % by area and 8.7±12.7 (0.1–52.8) % by UD (7 families, N=24). Overlap for non-breeding groups has a tendency to exceed ones for breeding families. Obtained summer home ranges are ones of the smallest for the species. Though island syndrome could be the main factor, the abundance of food resources has also reduced home range size but not territoriality which was strengthened by presence of pups.