THE ARCTIC FOX
Svalbard’s second largest predator on land is the Arctic fox. This curious little fox is highly adapted to a varying food supply. In summer it specialize in stealing bird eggs or chicks. In the winter it must endure long, cold days with little food, and sometimes encounters human settlements while in search of food. Today, there are thousands of Arctic foxes on Svalbard.An Arctic fox climbing a rock to get a better view of the surroundings. Copyright: Roy Mangersnes
The Arctic fox has a circumpolar distribution. It often travels across sea ice, and there have been found very limited genetic differences within the population across the world. This indicates a big gene flow (fox migration) between the different areas.
The Arctic fox on the mainland has a very variable breeding success that coincides with rodent population cycles. More rodents increase the breeding success of the fox. However, in Svalbard, there are no rodents except a limited area around Longyearbyen. This means that the fox population in Svalbard have to rely on stored food from the seabird breeding season and to eat carcasses left over from the Polar bear. Some foxes also kill and feed on Ringed seal pups in the seal birthing season.
The Arctic fox comes in two different color morphs – white and blue. The white changes to a brown thin grey summer fur, while the blue morph is blueish/grey in winter and dark chocolate brown in winter. The white morph is by far the most common (about 97%) in Svalbard, but both morphs occur.
The white winter fur of the Arctic fox, is considered the best insulating fur of all animals in the world. In fact, the insulation is so good that the fox does not need to increase its metabolism to keep warm before the temperature drops below minus 50 degrees Celsius.
The Arctic fox in Svalbard catch much more prey than it can eat during the short and productive summer. The surplus food is stored in the ground, so the fox can find it back during winter when food is scarce.
The fox has a very low survival rate during their first year of life. In Svalbard, only about 36% survive until 1 year old.
Arctic fox in summer coat on Spitsbergen. Copyright: Roy Mangersnes
A Arctic fox has taken a common eider egg from the nest and brings it to the den. This fox is changing from winter to summer coat. Copyright: Roy Mangersnes
An Arctic fox in winter coat is feeding of a Svalbard reindeer carcass. Copyright: Roy Mangersnes