Body-size comparisons of alpine- and forest-wintering woodland caribou herds in the Yukon

• Published in: Canadian Journal of Zoology
• Main Authors: Kuzyk, Gerald W, Dehn, Michael M, Farnell, Richard S
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1999
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; caribou; Rangifer tarandus; Yukon
• Online Access: http://dx.doi.org/10.1139/z99-053; http://www.nrcresearchpress.com/doi/pdf/10.1139/z99-053

Information from radiotelemetry studies has shown that woodland caribou (Rangifer tarandus caribou) living in the snow-shadow region of the southwest part of the Yukon spend part of the winter in the subalpine and alpine zones. Other woodland caribou living in areas with high snowfall in central and eastern Yukon have traditional winter ranges in forested lowlands. We theorize that selective forces exerted by the wintering environments will have induced differences in caribou body characteristics, and we test the hypothesis that woodland caribou that winter in the alpine zone are phenotypically different from those wintering in forested environments. We compared five physical measurements from 382 female woodland caribou in 11 Yukon herds. Our results indicate a significant (14 cm) difference in shoulder height between forest- and alpine-wintering groups, but provide no support for the hypothesis that the difference is due to snow depth. There were no significant differences in other body measurements or in body proportions. It is also unlikely that the difference in shoulder height is due to winter nutrition, since body condition scores did not differ between forest- and alpine-wintering groups. We discuss seasonal nutrition, predation, and migration as alternative explanations for our results.