Food Selection During Early Lactation by Caribou Calving on the Tundra in Quebec

Abstract

The ranges of two large caribou herds, the Riviere aux Feuilles and Riviere George herds, were sampled in June and July 1988 to compare vegetation composition. Lichens occupied more than 50% of the ground cover at Riviere aux Feuilles, whereas mosses, bare soil, and graminoids prevailed at Riviere George. Shrubs were more abundant on Riviere aux Feuilles, but the difference was not significant. Plant cover was similar whether sampling sites were selected at random or based on the presence of caribou. Within a season, diets of lactating caribou determined from analyses of rumen contents reflected the differences in vegetation cover. In June, lactating females from the Riviere George herd ate fewer lichens than those of the Riviere aux Feuilles, whereas in July their rumen contained fewer leaves of deciduous shrubs. In Riviere George caribou, graminoids compensated for the low lichen and leaf content in both collection periods; these animals exerted a high selection, particularly for lichens, which were 25 times less available but only 1.5-2 times less abundant in rumina. In July, fragments of Cladina sp. and leaves of Betula glandulosa were especially scarce in Riviere George samples. Protein contents of washed rumen samples were lower for both periods at Riviere George. This pattern of food selection by Riviere George caribou may be due both to long-term grazing of the summer range and to eco-climatic differences.