Responses of bison on their calving grounds to predation by wolves in Wood Buffalo National Park

• Published in: Canadian Journal of Zoology
• Main Authors: Carbyn, L. N., Trottier, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1987
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Canada; Wood Buffalo; Wood Buffalo National Park
• Online Access: http://dx.doi.org/10.1139/z87-317; http://www.nrcresearchpress.com/doi/pdf/10.1139/z87-317

Bison-wolf interactions were observed from a tower located in the centre of a meadow in Wood Buffalo National Park, Alberta, Canada, from 10 May to 9 September 1980. Special attention was directed to the relationship between bison cow-calf interactions, calf pod formations, and wolf predation attempts. Pod formation began in May and peaked in June. During 102 days in the field, 166 encounters between wolves and bison were observed, of which 51 involved a single wolf interacting with bison. In the main, single wolves watched bison (23% of observations), trailed without follow-up (14%), trailed with follow-up (27%), or harassed them without making physical contact (34%). Only rarely (2% of the observations) did they attack. The remaining 115 encounters involved a pack of wolves (two or more individuals). The majority of them involved trailing with follow-up (26%) or harassment (48%), and rushing with physical contact (13%). Wolves, especially those in packs, preferentially attacked bison herds with calves over herds without calves. Single wolves were more likely than wolves in packs to attack herds of bulls only (34 vs. 5% of such encounters). Strategies used by bison in defence of their calves were recorded along with the hunting strategies employed by wolves.