Predation on an introduced vole Microtus rossiaemeridionalis by arctic fox Alopex lagopus on Svalbard

Abstract

The arctic island group of Svalbard has no native species of voles or lemmings, but the vole Microtus rossiaemeridionalis has been accidentally introduced. Mainly found in the region of the abandoned Russian mining town of Grumant, the vole has not been able to colonise larger parts of Svalbard. The food habits of arctic foxes Alopex lagopus were studied by collecting and analysing samples of scats from various sites in the region in 1996, including fresh scats from three litters. Hairs of voles were found in scats from all sites, but the proportion of voles in the diet of arctic foxes varied considerably. Overall, voles made up 13% of the diet by occurrence, but were insignificant in the diet of the three litters. Birds were the most important (79%) and reindeer carcasses the second most important food item (22%). Other estimates used gave less importance to voles (10 and 4%). Birds most often constituted the major part of a scat, voles less often. Pups from three litters had consumed 97% birds, with the proportion of alcids and gulls varying largely according to availability near the respective litter. The population of voles at Grumant was very low in 1996, but in other years it may grow to much higher numbers. However, a large proportion of the scats collected were old and reflected arctic fox diet over many years. Although arctic foxes at Grumant have gained access to a new food source, voles appear to be of minor importance in their diet.