Title

Variability In Marine Resources Affects Arctic Fox Population Dynamics

Keywords

Allochthonous resources; Indirect effects; Numerical response; Scavenging; Stable isotope ratios

Abstract

1. Terrestrial predators in coastal areas are often subsidized by marine foods. In order to determine the potential impact on terrestrial prey, the numerical response of predators to each food source must be determined. 2. In winter, arctic foxes (Alopex lagopus) may forage on the frozen Arctic ocean and scavenge carcasses of seals killed by polar bears (Ursus maritimus), but the importance of this food source and its effect on the population cycles of arctic foxes and lemmings (their primary prey) are unclear. 3. I estimated the marine component of the late winter diet of arctic foxes near Churchill, Manitoba, using stable-carbon isotope analysis, and compared these estimates to abundance of arctic foxes and collared lemmings (Dicrostonyx richardsoni). 4. From 1994 to 1997, fox density varied with lemming abundance, but following a decline, fox abundance began increasing before lemmings. During this increase marine foods were consumed more than in other years, with over two-thirds of food intake from marine sources. 5. Arctic and red fox (Vulpes vulpes) harvests in the 1980s to 1990s were correlated with published estimates of polar bear body mass, which varies with seal productivity. However, this relationship disappeared during high lemming years. 6. Thus, variation in marine productivity affects arctic fox abundance, especially when their primary prey are scarce, and this numerical response of arctic foxes to marine resources and lemmings suggests that increased predation by arctic foxes subsidized by seal carrion may delay the recovery of low lemming populations.

Publication Date

7-1-2003

Publication Title

Journal of Animal Ecology

Volume

72

Issue

4

Number of Pages

668-676

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1046/j.1365-2656.2003.00739.x

Socpus ID

0038044766 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0038044766

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