Our mammalogist Alexander Shiyenok spent December and January in research of the arctic fox winter ecology and other mammals of Bering Island. As we remember, his first experience of in-depth research in this field was in March 2017 (http://komandorsky.ru/en/arctic-fox-counts.html). The research showed that even though March can be seen as a winter month on the Commander Islands, certain changes in arctic fox behavior start to appear. They are connected with the upcoming breeding season. The arctic fox shows territorial behavior. The animals search for partners, clear and guard their breeding burrows.