The importance of prey distribution in habitat use by arctic foxes (Alopex lagopus)

Abstract

The use of habitat by reproducing arctic foxes (Alopex lagopus) in relation to prey distribution was examined on the Svalbard archipelago in the Norwegian High Arctic during 1987–1988 and 1997–2000 by means of VHF telemetry. The distribution and abundance of the main prey species of foxes was registered in 4 separate periods during summer. The availability of 9 habitat types was estimated on the basis of a classification of a Landsat-5 TM scene. Three resource areas that differed with regard to distribution and availability of prey, vegetation, and terrain were identified within the study area: (1) inland areas with no geese, (2) inland areas with geese present, and (3) coastal areas with bird cliffs. The use of resources by foxes was calculated in the 4 separate periods, as was the average speed of movement (m/h) of foxes and the distance between fox locations and their natal dens. Resource-selection functions (RSFs) calculated for individual animals showed that resource use was nonrandom and similar for foxes that lived within the same resource area. In inland areas in which resource availability was low but fairly stable (area 1), RSFs were simple and in some cases of low significance compared with a no-selection model. In inland areas with highly dynamic resources (area 2), RSFs were complex and resource use differed significantly between periods. In coastal areas (area 3), where resources were plentiful, highly concentrated, and stable, RSFs were of intermediate complexity and resource use differed less between periods.