The Decline of the Arctic Fox in Scandinavia

The arctic fox has lived in the Scandinavian countries of Norway, Finland, and Sweden since the last Ice Age, which ended more than10,000 years ago. Today, however, the arctic fox in Scandinavia is in severe trouble. Despite intense conservation efforts, its numbers have been radically declining. Why this most resourceful of species has been unable to rebound since hunting was prohibited is not altogether clear.

One possibility is that the animals have gone through what biologists refer to as a population bottleneck. Such bottlenecks occur when the number of animals in a given population is reduced to the point where inbreeding enables the enhanced proliferation of genes that may be detrimental to a species' overall fitness (ability to survive). A related hypothesis is that the arctic foxes had lost their genetic advantage owing to the spread of genes from selectively bred foxes that escaped from farms. Captive-raised foxes are known to have escaped, and recent genetic studies from Norway have shown that such interbreeding between farm-bred foxes and foxes in the wild has indeed taken place. While these results are being viewed as potential future trouble, there is still no indication that they explain past difficulties. The number of crossover genes detected in the Norwegian study was small, suggesting that mixing between wild and escaped foxes is a recent occurrence.

Among changes in the environment that might be to blame, one of the earliest ideas relates to the absence of wolves, animals that for thousands of years filled the role of top predator throughout Scandinavia but that disappeared from most of Norway and Sweden during the twentieth century after hundreds of years of persecution. There is no winter sea ice along the coastlines of Norway and western Russia, as there is throughout the Canadian Arctic and off the coast of Siberia, meaning the arctic foxes in this part of the world have no access to remains of polar bears' prey, an important source of food for arctic foxes. What they do have access to is reindeer. Since wolves are the only predator of reindeer in Scandinavia, it has been argued that the elimination of the wolf has led to a decline in the availability of a necessary winter food supply.

Scientists, however, have been unable to uncover any strong evidence to support the claim that arctic foxes are suffering because of the absence of large predators. One study even suggests arctic foxes do better in the absence of large predators because when animals such as reindeer die of natural causes, the foxes have the large carcasses all to themselves. Also casting doubt on the wolf's culpability is the fact that it had been hunted out of many alpine regions of Scandinavia during the mid-nineteenth century, long before the arctic fox entered into its decline. What's now known about wolf biology suggests the amount of meat and entrails (internal organs) left behind by these animals may not be sufficient to have a noticeable impact on the arctic fox population.

Today there is little enthusiasm among arctic fox scientists for the idea that a lack of wolves is to blame. Instead, most now believe the trouble stems from the increased presence of another canine carnivore- one that, in the eyes of the arctic fox at least, is far more ferocious: the red fox. The red fox is one of the most successful carnivores anywhere. It has evolved a repertoire of instincts that has enabled it to thrive in a world increasingly dominated by humans and human-altered landscapes.

For the most part, arctic foxes and red foxes occupy different environmental niches. Generally the arctic fox keeps to the tundra, while the red fox is at home in a wide range of habitats throughout the northern hemisphere. In recent decades, however, there is evidence that red foxes are increasingly encroaching on what previously had been territory inhabited only by arctic foxes. During the nineteenth century, there were occasional red fox sightings on southern Baffin Island in Canada, but none of the animals were known to settle down and breed. In the last half of the twentieth century, however, they returned and became a permanent population there.