Coyote foraging ecology and vigilance in response to gray wolf reintroduction in Yellowstone National Park

Coyotes (Canis latrans) in Yellowstone National Park (YNP) have lived in the absence of wolves (Canis lupus) for over 60 years. I examined whether wolf reintroduction in 1995 and 1996 in YNP influenced coyote vigilance and foraging ecology. From December 1997 to July 2000, my co-workers and I collected 1708 h of coyote activity budgets. Once wolves became established in the Park, they once again provided a continuous source of carrion in the Lamar Valley and we found that coyotes began feeding on carcasses throughout the year. Although we documented that wolves killed coyotes, it also became clear that surviving coyotes quickly adjusted their behaviors when wolves were present. When coyotes were near wolves or in areas of high wolf use, they fed on carcasses much more; however, they increased the amount of time spent in vigilance activities and decreased rest. There appears to be a trade-off in which wolf kills provide a quick source of food that is energetically advantageous to coyotes; however, attendant costs included increased vigilance, decreased rest, and a higher risk of being killed. Changes in the behavior of coyotes in response to the reintroduction of this large carnivore may ultimately have wide-ranging cascading effects throughout the ecosystem.