Habitat and Predators

An arctic fox sitting atop a rock outcropping. Photo permission pending.

Arctic foxes are found all over the Arctic Circle (Postanowicz para. 1), where they make extensive use of dens for living, caching food, breeding, and as protection from predators. The main determinant of habitat use is proximity to food sources, with den sites correlating significantly with prey breeding and feeding sites. Arctic foxes thus prefer high-alpine and coastal areas with strong topographical variation over woodland and heath environments because that is where their prey is mostly found (Jepsen et al. 2002). Variation in alpine fox habitat use seems to result from variation in prey habitat use, as arctic foxes frequently change habitat in areas where prey move a lot, such as near geese populations, and are more stationary when habitat sites are spatially close to prey, such as in coastal areas with large, relatively centralized prey like seabirds (Jepsen et al. 2002). There is no evidence of seasonal shitfts in habitat usage (Jepsen et al. 2002).

Arctic fox dens are generally located on slopes or valleys offering unrestricted views (Prestrud 1992b). Dens are almost always located in frost-free zones under protruding bedrock or under boulders, which tend to be drier and receive less snowfall. Dens are comprised of a system of tunnels ranging from 30 to 50 square meters, with immense variation in number of entrances (Tannerfeldt para. 3), with an average of approximately 10 (Prestrud 1992b). Some dens have been used for hundreds of years by arctic foxes (Tannerfeldt para. 3), likely in areas with low spatial and temporal variability in prey location.

Predation pressure is relatively low for the arctic fox relative to most species, as mange infections, low population numbers, and low and irregular food availability seem to be bigger threats (Tannerfeldt, para. 20). Birds of prey, particularly snowy owls and golden eagles have been known to prey on arctic fox young, while terrestrial predators such as wolverines and polar bears are also prey on arctic foxes (Postanowicz para. 8) even into their adulthood. In the early 20th century, prices were high for the foxes' coveted fur coats, and hunting reduced the arctic fox population drastically. Despite complete protection since 1940, the population has not recovered, and Swedish arctic foxes remain threatened by extinction (Elmhagen et al.2002).

One of the arctic fox's greatest modern threats is the red fox, which, because of its larger size, almost always has the advantage in agonistic encounters (Frafjord et al., 1989). Red foxes compete with arctic foxes over food (Elmhagen et al., 2002), and habitat sites (Frafjord et al., 1989). The spatial are in which red foxes and arctic foxes are sympatric is somewhat narrow, as red foxes' larger size necessitates higher prey densities that are rarely found in the higher altitudes that arctic foxes frequent (Elmhagen et al., 2002). Despite this narrowness, red foxes pose a significant threat to the near-extinct population of arctic foxes.

 

This page was created by Philip Newsom in partial fulfillment of the requirements for Biology 323, Animal Behavior, at Davidson College in the Spring Semester 2007. Please send any comments, questions, or suggestions regarding this web site to Philip or Dr. Verna Case