Wily Canis latrans, the coyote, was the cock of the walk in Yellowstone National Park for nearly a century. But when the first reintroduced wolves stepped out of their pens in Yellowstone after being absent during that time, it was an "oh-oh" moment for the park's coyote population.
Many researchers expected as much and the fact that coyotes and wolves don't exactly get along is nothing new. Indeed, the famous naturalist J. Frank Dobie wrote in 1947 that the West-wide extermination of the wolf was undoubtedly to the coyote's benefit. Dobie's prognostication bore fruit; coyotes now range from the outskirts of New York City to the streets of Los Angeles, a stretch of country that has actually increased despite intense persecution on coyotes from mankind.
But in Yellowstone in 1995, Old Man Coyote found a whole different story.
Today, wolves are healthy in the park and coyotes are rarer. Researcher Bob Crabtree has noted that the previously-abundant coyotes have dropped off fifty percent from pre-wolf years. Competition is part of the picture, but wolves also kill coyotes. Eighty to ninety percent of coyote deaths from wolves take place at kills, where Wily Coyote is not quite so sneaky and gets a little too close to his larger brethren.
For other animals, this can be good news. Pronghorn antelope fawns, for instance, are frequent prey of coyotes. Anecdotal evidence so far is showing that Yellowstone's pronghorn population is doing better, with better fawn survival where wolves are present to keep coyote populations down. In fact, where coyotes are abundant, fawn survival has been documented as almost nonexistent. A researcher in Grand Teton National Park has seen and recorded evidence that shows that the presence of wolves is a direct benefit to pronghorn because the big canines knock back the coyote population.