Diet overlap of collared lemmings and tundra voles at Pearce Point, Northwest Territories

Abstract

We used a combination of faecal pellet analysis and feeding enclosure trials to determine the diets of collared lemmings (Dicrostonyx kilangmiutak) and tundra voles (Microtus oeconomus) at Pearce Point, Northwest Territories, and we looked for evidence of exploitative competition between the two species. Voles preferred monocotyledons (Carex and Eriophorum spp.) and lemmings preferred Dryas integrifolia. We found that there was little overlap in the natural diets of the two species, but that overlap was increased experimentally when both species were forced to forage in the same habitats. However, food preferences generally did not change. The diet of collared lemmings at Pearce Point was similar to that found in all other studies except those done in Alaska, where Dryas is uncommon. We conclude that exploitative competition for food is unlikely to be an important factor in interspecific relations between collared lemmings and tundra voles.