In Minnesota, as wolves expanded their range in one northern area, they completely eliminated a dozen radio-collared coyotes, says Bill Berg, a wildlife biologist with the Department of Natural Resources in Grand Rapids. To avoid the wolves, the coyote population has shifted south. Gese says he thinks the situation in Yellowstone will probably mimic that in Montana's Glacier National Park, where wolves arrived on their own from Canada in about 1986 and began reestablishing themselves. Wendy Arjo of the University of Montana in Missoula has been studying 18 radio-collared coyotes in the park over the past 3 years. She compares her observations with those from a 1980 study, before the wolves returned.
Predators do take a heavy toll.
Three others are unaccounted for. She has noted other changes in the population. The coyotes have moved away from wolf territories and changed their diet, eating fewer hares and more ungulates, probably from scavenging wolf kills. Perhaps the most interesting change is morphological. The average male coyote has grown from 11.8 kilograms in 1980 to 13.9 kg.