Life can be hard when you are an elk living in Yellowstone National Park. As one of the park’s most abundant species, elk must compete with their fellow inhabitants for food, shelter, and other resources. On top of that, elk are prey for at least 15 predator species and account for approximately 90% of all winter-time wolf kills. While the secrets to elk survival have remained largely mysterious, scientists have now uncovered new insight into how they simultaneously minimize the threat of multiple predator species.

Past research on predator-prey relationships in the wild has tended to focus on only one species from each group, like the famous lynx-snowshoe hare study system. In the present study, a team of ecologists from Utah State University gathered GPS data from several radio-collared animal species within Yellowstone: wolves, cougars, surviving elk, and elk that were killed by wolves and cougars. They first discovered the predator species had distinct hunting behaviors; wolves hunted primarily in grassy areas during morning and evening hours, while cougars stuck to forested areas and preferred to hunt at night. Interestingly, surviving elk took advantage of these patterns by specifically avoiding the hunting domains of both predators at the appropriate times of day, allowing them to thrive despite the near constant threat of being hunted.

While the conclusions of this research may seem simplistic, it is one of the first studies directly supporting the “vacant domain hypothesis”—the notion that prey avoid multiple predators simultaneously by inhabiting various locations at times when predators are least active. This is in contrast to the long-standing idea that avoidance of one predator by a prey species increases its exposure to other predators. Considering that elk are hunted by over a dozen species at Yellowstone, future studies incorporating GPS data from even more predators could shed further light on the complexities of how many elk manage to stay off the daily menu.

Managing Correspondent: Benjamin Andreone

News Article: Fearing cougars more than wolves, Yellowstone elk manage threats from both predators.

Original Article: Do prey select for vacant hunting domains to minimize a multi‐predator threat? Ecology Letters

Image Credit: Pixabay

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