The Eleventh North American Caribou Workshop, Jasper, Alberta, Canada, 24-27 April, 2006. Woodland caribou persistence and extirpation in relic populations on Lake Superior Arthur T. Bergerud1, W. J. Dalton2, H. Butler1, L. Camps3, & R. Ferguson4 1 1233 Isabella Road, Salt Spring Island, British Columbia, Canada V8K 1T5 (
[email protected]). 2 Ministry of Natural Resources, 70 Foster Drive, Suite 400 Sault Ste. Marie, Ontario, Canada P6A 6V5 (
[email protected]). 3 220 Hillcrest Drive, Salt Spring Island, British Columbia, Canada V8K 1Y4 (
[email protected]). 4 5275 Leeward Run Drive, Alpharetta, Georgia, U.S.A. 30005 (
[email protected]). Extended abstract: The hypothesis was proposed that woodland caribou (Rangifer tarandus caribou) in North America had declined due to wolf predation and over-hunting rather than from a shortage of winter lichens (Bergerud, 1974). In 1974, two study areas were selected for testing: for the lichen hypothesis, we selected the Slate Islands in Lake Superior (36 km2), a closed canopy forest without terrestrial lichens, wolves, bears, or moose; for the predation hypothesis, we selected the nearby Pukaskwa National Park (PNP) where terrestrial lichens, wolves, bears, and moose were present. Both areas were monitored from 1974 to 2003 (30 years). The living and dead caribou on the Slates were estimated by the ‘King census’ strip transect (mean length 108±9.3 km, extremes 22-190, total 3026 km) and the Lincoln Index (mean tagged 45±3.6, extremes 15-78). The mean annual population on the Slate Islands based on the strip transects was 262±22 animals (extremes 104-606), or 7.3/km2 (29 years) and from the Lincoln Index 303±64 (extremes 181-482), or 8.4/km2 (23 years).