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Variability in marine resources affects arctic fox population dynamics
Article first published online: 3 JUL 2003
DOI: 10.1046/j.1365-2656.2003.00739.x
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How to Cite
Roth, J. D. (2003), Variability in marine resources affects arctic fox population dynamics. Journal of Animal Ecology, 72: 668–676. doi: 10.1046/j.1365-2656.2003.00739.x
Publication History
- Issue published online: 3 JUL 2003
- Article first published online: 3 JUL 2003
- Received 11 October 2002; accepted 24 March 2003
- Abstract
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Keywords:
- allochthonous resources;
- indirect effects;
- numerical response;
- scavenging;
- stable isotope ratios
Summary
- 1Terrestrial 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.
- 2In 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.
- 3I 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).
- 4From 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.
- 5Arctic 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.
- 6Thus, 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.