Fox and Coyote Trapping Records Reveal the Major Impact of Wolves Across North America

It turns out that wolves have a greater influence than expected when it comes to smaller predators further down the food chain. Using coyote and red fox fur trapping records, scientists have recorded how these larger predators influence the ecosystem around them.

"As wolves were extirpated across the southern half of North America, coyotes dramatically expanded their range," said Thomas Newsome, one of the researchers, in a news release. "They were historically located in the middle and western United States, but they dispersed all the way to Alaska in the early 1900s and to New Brunswick and Maine by the 1970s."

As coyotes have expanded, they've actually become a major concern for the livestock industry. In fact, researchers estimated that losses due to coyote predation on sheep and cattle was about $40 million in 2004.

By examining trapping records, the researchers showed that the "wolf effect" actually exists. This means that where wolves are present, red foxes are favored. In contrast, coyotes are favored where wolves are absent. This effect requires that enough wolves be present to suppress coyotes over a wide area.

"So essentially coyotes have been dispersing into wolf and red-fox range in the north but also into areas where wolves are absent but red fox are present in the east," said Newsome in a news release.

The findings have implications for ecological conservation practices. More specifically, it shows how wolves can have a large impact on their surrounding environment. Previous studies have shown that wolves impact herbivores which, in turn, influences the vegetation present in a certain environment.

"This study gives us a whole other avenue to understand the ecological effects of wolves on landscapes and animal communities," said William Ripple, one of the researchers, in a news release.

The findings are published in the Journal of Animal Ecology.