Range Ecology of the Porcupine Caribou Herd in Canada

Abstract

The PCH migrates from summer range on the arctic coastal plain of Alaska and Yukon to winter in the forested valleys and plains of north-central Yukon and western Alaska. Lichen biomass in winter range averaged 65 g/m2, mainly Cladina and Cetraria. mean fire interval of 120 yrs. Lichen biomass tended to decline with stand age for all genera except Cetraria. Animals moved an average of 10.9 km/day during insect harassment season. Near end of mid-summer period, a shift toward more lichen in diet occurred, although deciduous shrubs and forbs dominated the summer diet. 'Total lichen biomass declined with age class (classes of 0-50 yrs, 51-125, 126-211, 212-275, and >275).' but Cladonia spp. peaked between 51-125 yrs. Cetraria increased with age. Stereocaulon decreased significantly after 50 yrs. Fecal pellets: differences in diets over winter and among years were examined with a Kruskal-Wallis test for the major food groups. Age of stands determined by tree disks cut at ground level. Winter range not one of the most critical habitats for PCH. Lichen biomass measured prior to green-up: 25cm x 25 cm plots cut and oven dried.From executive summary (page 14): 'The large Porcupine Caribou Herd of Grant's caribou (Rangifer tarandus-granti) migrates annually from summer range on the arctic coastal plain of Alaska and Yukon to winter in the forested valleys and plains of north-central Yukon and western Alaska. Concern for the well being of the herd in response to existing and proposed developments within their range, and the need for more knowledge on the range ecology of the species prompted this study. The work was conducted primarily by the Canadian Wildlife Service, initially as a joint project with the Yukon Department of Renewable Resources and continued from 1979 to 1987. We have divided the report into three major chapters, covering the winter, the late spring and the summer. Throughout these chapters we refer to 15 periods in the annual life cycle of the herd. In the final chapter, we discuss the energetic implications of our findings.