Variation between Snow Conditions at Peary Caribou and Muskox Feeding Sites and Elsewhere in Foraging Habitats on Banks Island in the Canadian High Arctic

Abstract

Between October 1993 and May 1998 we measured snow depth (cm), density (g cm⁻³), and resistance (kg × cm) adjacent to 53 Peary caribou (Rangifer tarandus pearyi) and 134 muskox (Ovibos moschatus) feeding craters on Banks Island in the Canadian High Arctic. Measurements were taken in early (26 October-18 November), mid- (12 February–1 March), and late-winter (20 April–4 May). Concurrently, we recorded snow depth, density, and resistance along fixed transects in the four habitats used by foraging caribou and muskoxen. Caribou craters were found predominantly (94%) in upland habitats; upland barren (UB), hummock tundra (HT), and stony barren (SB). Caribou abandoned craters in the more rolling UB and HT when snow was shallower, less dense, and less resistant than average snow conditions in these habitats; in most cases the differences were significant (P < 0.01). In SB, the habitat with the shallowest snow, caribou cratered through snow conditions similar to the average found in this habitat. During winter 1994–95, when snow depth, density, and resistance was greatest, we located caribou craters only in SB. Muskox craters were found almost exclusively (96%) in wet sedge meadows (WSM); the habitat with deepest snow. Muskoxen abandoned crater sites when snow depth, density, and resistance was less (P < 0.01) than average conditions in WSM, regardless of animal density. Muskoxen in low density areas were faced with deeper snow, particularly in late- winter, and they abandoned crater sites when snow depth was greater (P < 0.004) than muskoxen in high density areas. During winter 1994–95, muskox cratered through deeper, denser, and more resistant snow than during winter 1997–98 when snow conditions were the least severe of the study. We discuss our results in relation to the population dynamics of Peary caribou and muskoxen on Banks Island.