The Effect of Extreme Snowcover on Feeding-Site Selection by Woodland Caribou

Abstract

The depth and hardness of snowcover are important factors affecting caribou (Rangifer tarandus) feeding strategies. We investigated the influence of extreme snow conditions on the distribution and use of feeding sites by caribou in the Red Wine Mountains Region, Labrador, during winter (Dec-Apr), 1982-83 and 1983-84. The tolerance of caribou to snowcover depth and hardness exceeded all previously reported thresholds. Caribou wintered in areas with mean snow depths of 176.7 cm and, to reach forage, they dug through snow with mean depths of <123.1 cm. Snowcover depths and hardnesses were similar between feeding areas and adjacent areas of similar habitat. Evidence indicated that caribou are capable of visually distinguishing among snow covered terrain features to locate forage on the ground. J. WILDL. MANAGE. 54(1):161-168 Snowcover depth and hardness affect the ability of caribou to smell forage growing on the ground (Bergerud and Nolan 1970) and the amount of energy expended to reach forage (Thing 1977, Fancy and White 1985). Across North America, when threshold tolerances of caribou to snow depth and hardness are exceeded, caribou reportedly feed on arboreal lichens or move to seek more favorable conditions (Pruitt 1959, Henshaw 1968, Stardom 1975, LaPerriere and Lent 1977). However, thresholds have been determined only where mean maximal snowcover depths ranged between 45 and 80 cm, and where the greatest depths in habitats used by caribou seldom exceeded 90