Coyotes and gray wolves have coexisted in western North America for a very long time, but gray wolves were driven to near extinction in the U.S. by the 1920s. For 70+ years, coyotes lived in the absence of wolves in Wyoming’s Yellowstone National Park until wolves were gradually reintroduced into the park by the U.S. Fish and Wildlife Service in the mid 1990s.
Along with our partners at the Yellowstone Ecological Research Center (YERC), we have been studying coyote feeding ecology over the past two decades to examine the potential effects of environmental change, including climate change, prey availability, and the reintroduction of wolves.
Western gray wolves are much larger than western coyotes and they will actively make life difficult for coyotes, at times even killing them. However, wolves prey upon large animals like elk and moose, and the partially eaten carcasses they leave behind can provide food opportunities for coyotes who are willing to risk their lives for an easy meal.
We have analyzed nearly 1,200 samples of coyote scat that were collected in Yellowstone between 1990 and 2006 as a way to gain insight into coyote diets over time. These results are being compared to corresponding climate data, annual large animal carcass counts, and yearly and seasonal changes in small mammals which coyotes eat.
Preliminary analysis shows that coyote diets did change after wolves were introduced. We are currently working on a manuscript that we hope to publish soon.