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.
Alexander Shiyenok on winter monitoring trail
This year we decided to conduct monitoring in the middle of the winter season. It allows us to observe behavior not connected with bringing up the young. Another interesting theme is how arctic foxes manage to overcome food shortage in winter. Finally, winter is the best time to collect fecal samples for further helminth tests. Tabletop analysis showed that a big part of the arctic fox population is contaminated with different types of helminths. We found 4 helminth species, which has never been described to be found in Bering Island arctic fox.
Trails of arctic foxes showing that the animals were searching for food. Photo by Alexander Shiyenok
Last year we mainly worked in the northern part of the island. In 2018, we chose Buyan Bay in the middle of Bering Island and in the buffer zone of the biosphere reserve. The bay is valuable for winter scientific research, because inspectors monitor the territory nearly all year round. Moreover, recently we upgraded local infrastructure, which improved significantly working conditions in the area. Partly the research took place in the northern part of Bering Island, namely near Sarannaya River, which takes off from the cognominal lake – the largest spawning site of the island.
Cabin in Buyan Bay. Photo by Alexander Shiyenok
As a result we collected a lot of fecal samples, analyzed food debris, made dissection of a number of northern red-backed voles (to estimate the proportion of individuals contaminated by alveococcus), counted population numbers of the arctic fox and other wintering species. Parasite tests of the samples collected last year showed high contamination levels in arctic foxes living near Sarannaya River. That is why this year the research continues.
Buyan Bay. Photo by Alexander Shiyenok
During the monitoring period, the numbers of arctic foxes in Buyan Bay varied depending on the day. In the beginning, the numbers grew quickly and one could spot up to 16 individuals at the same time on the nearest hill. After the storm came, nearly all the animals disappeared and the numbers remained low until the very end of monitoring period. We still do not fully understand the reasons of such travels. We can only take a guess, that stormy weather became a signal for the animals to search for food in the coastal area. Large numbers of arctic foxes here may be connected with humpback salmon pieces remained after summer fishing. According to another theory, arctic foxes wait for ice fishers to get some char from them. On the other hand, during the monitoring period, the ice was not solid enough and there were no fishers. May be it became the impulse for the animals to search for new food sources.
Winter is an extremely difficult period for arctic foxes to survive. Photo by Alexander Shiyenok
The monitoring also showed that in winter arctic foxes are more likely to eat cormorants. They may be a relatively easy prey for the arctic fox. Or the reason may be in high death rates of cormorants in winter. Several dead cormorant have been found eaten by ravens, which may be an evidence to that theory. The second place in arctic fox preference list is occupied by codfish heads (who ate the fish body is unknown). The third place goes to dead sea otters. In general, in winter arctic foxes eat everything they can find.
Not many arctic foxes were spotted near Sarannaya River this year, including three animals tagged in 2017. They are attracted to the area by coho salmon , which spawns here till January and some dead individuals remain here till march. After taking the samples, the parasitologists started the analysis immediately and found two new parasitic species. Moreover, they confirmed alveococcus presence in voles from Buyan Bay.