(Montana State University - Bozeman, College of Letters & Science, 2006) Winnie, John Arthur, Jr.; Chairperson, Graduate Committee: Scott Creel
We studied individual and herd level behavioral responses of elk to spatial and temporal variation in the risk of predation by wolves over three winters in the Upper Gallatin drainage, Montana. Within a given drainage, elk of both sexes moved into or closer to protective cover (timber) in response to wolf presence. Cow elk responded to elevated risk by increasing vigilance in exchange for foraging, and large mixed (cow, calf, spike) herds substantially decreased in size. In contrast, when wolves were present, bulls did not increase vigilance levels, nor decrease feeding, and small bull-only groups slightly increased in size. As a consequence, small bull-only herds and large mixed sex herds converged on a similar size when wolves were present.
