Prey Responses to Re-Colonizing Wolves and Grizzly Bears

Authors(s): J. Berger

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Publication Date: 0000-00-00

Type: annual report

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Abstract: Objectives The recent extinction of wolves and grizzly bears from 95-99% of the contiguous USA and Mexico has altered predator-prey dynamics. The primary objective of this work is to evaluate how varying predation pressure (contemporary, past, and novel) affects bison, elk, and moose. This type of information is necessary to understand how current predation, and its loss and restoration, shapes prey ecology and behavior. Ungulate responses to potential predators and scavengers will be evaluated by gathering data on foraging rates when exposed to simulated sounds of wolves, ravens, and novel and neutral stimuli projected through a speaker. Comparison have already been completed with predator exposed bison and elk and moose from northern circumpolar environments. Findings and Status Moose have demonstrated to date the most complex responses to olfactory and auditory playbacks. Where predation has occurred on offspring, mothers terminate feeding at higher rates to canid calls and to bear odors than when offspring have survived. Alaskan moose are more sensitive to scavenger and carnivore cues than Wyoming moose. In Wyoming however, predation rates on newborns have generally been low, and the disproportionate fewer offspring found in GTNP and surrounding environs is more likely due to low pregnancy rates. Bison from northern environments do not show greater sensitivity to the above cues than do bison from either Yellowstone or Grand Teton National Parks. However, the variance in responses are increasing in Yellowstone Park relative to Grand Teton park. Elk wintering in GTNP are more responsive to wolf vocalizations now than they were in 1997-1998. These latter responses are likely the result of increased predation by wolves. Continuing research is focusing upon the pace at which adaptive responses to predators occurs under varied predation pressure.

Keywords: moose, Alces alces, animal, mammal, ungulate, Grand Teton National Park, grizzly bear, bear, Ursus arctos horribilis, Ursidae, predation, wolf, canine, Canidae, Canis lupus, raven, Corvus corax, Corvidae, brucellosis, bison, Bison bison, Cervidae, elk, Cervus elaphus, wapiti, forage, Yellowstone National Park