Arctic Foxes face several types of threats resulting from global climate change. The most significant of these threats is probably the loss of the tundra habitat that the species inhabits. As warming temperatures allow new plant species from the south to colonize the region, large extents of tundra habitat are expected to slowly be replaced by boreal forest. Forest habitat is known to be highly unsuitable for Arctic Foxes (IUCN 2009).
Another threat to the Arctic Fox comes from Red Foxes, which compete with them for food and prey on Arctic Fox kits and adults. While the northern limits of the Red Fox’s range are determined by the productivity of the habitat, the southern limits of the Arctic Fox’s range are determined by the presence of the Red Fox. The encroachment of Red Foxes into more northern areas has already been documented and is likely to continue as the tundra warms (Fuglei and Ims 2008).
The changing climate also drives changes in prey abundance. Numbers of Arctic rodents, particularly lemmings, are known to fluctuate greatly, but historically such fluctuations have been fairly regular and cyclical. It is predicted, however, that climate change will lead to instability in the population sizes of these and other important prey species, such as voles. Lemmings and voles do not hibernate through the winter. Instead they continue to forage in the space between the frozen ground of the tundra and the snow, almost never appearing on the surface. This is possible because the snow provides good insulation from the severe Arctic winter conditions. Mild weather and wet snow lead to the collapse of these under-snow spaces, destroying the lemmings’ burrows, while ice crust formation reduces the insulating properties of the snow pack and may make food plants inaccessible. The combination of milder and shorter winters is predicted to decrease the regularity of lemming cycles, and population peaks in some populations have not occurred since the 1990s (IUCN 2009).
Any declines of important prey species are likely to have significant impacts on Arctic Fox populations. Declines of Arctic Fox numbers attributable to prey declines have already been observed in some Scandinavian populations. It is possible that although species such as lemmings may decrease in number, other potential prey species may begin to thrive in the new climate. Unfortunately for the Arctic Fox, the associated arrival of species such as the Red Fox would almost certainly cancel out any benefits from these changes (IUCN 2009). Arctic Foxes inhabiting coastal regions are likely to be less affected by declines of rodents than inland populations (Fuglei and Ims 2008). However, because Polar Bears and Ringed Seals are expected to decline due to climate change, coastal populations are likely to face reductions in alternative food sources such as Ringed Seal pups and the remains of Polar Bear prey (IUCN 2009).
Arctic Foxes are unable to persist in environments other than their native tundra habitat. This means that individuals living in southern parts of the species’ range will probably need to move north if they are to survive. Arctic Foxes, however, already occur in some of the most northerly parts of the world and their total available habitat is shrinking. This means that that the number of Arctic Foxes that can be supported worldwide is likely to decrease. Arctic Foxes living on Arctic islands may ultimately prove to be the safest of all populations. Such locations are generally at very high latitudes and will be among the last to face changes in tundra habitat and invasion by Red Foxes. Furthermore, the likely loss of the ice sheets currently connecting these islands to the continental landmasses will prevent access by Red Foxes (Fuglei and Ims 2008). However, island populations often tend to be more vulnerable to losses of genetic variation, which can cause health or reproductive problems.
