Difference in diet and age structure of blue and white Arctic foxes (Vulpes lagopus) in the Disko Bay area, West Greenland

The stomach contents of 41 Arctic foxes (Vulpes lagopus) killed during winter and spring (December to June 1991-93) on Disko Island were examined. Fish, seabirds and marine invertebrates were found to be the most important winter food for Arctic foxes on Disko Island. Most fish remains in the stomachs were identified as capelin (Mallotus villosus), and cached fish appear to be important winter food for coastal foxes in the Disko Bay area. The stomachs of blue foxes contained more fish and marine invertebrates than those of white foxes, and stomachs of blue males contained more fish than those of blue females and white foxes of either sex. The age of 26 foxes was determined by X-rays and counting of annual lines in canine root cementum. Almost all the white foxes but less than a quarter of the blue foxes were in their first winter when harvested. The results of this study suggest that most of the white foxes were immigrants to Disko Bay while the blue foxes originated locally.