Unafraid of the Big, Bad Wolf
March 4, 2008
The big, bad wolf could use a few friends. If western states remove the gray wolf from protection under the Endangered Species Act—a decision currently under debate—consequences could be grave. Wyoming and Idaho announced they would reduce their populations of approximately 300 and 700 wolves, respectively, by 50 percent and 80 percent.
Amidst the debate, Wildlife Conservation Society (WCS) researcher Dr. Kim Berger is speaking out on behalf of an unsuspecting wolf ally: the pronghorn antelope, North America’s fastest land animal. In a study published in the latest issue of the journal Ecology, Berger says that healthy wolf packs keep coyote numbers in check. Since coyotes—but not wolves—can prey heavily on pronghorn fawns, the fawns have higher survival rates when wolves share their ecosystem.
“People tend to think that more wolves always mean fewer prey,” says Berger. “But in this case, wolves are so much bigger than coyotes that it doesn’t make sense for them to waste time searching for pronghorn fawns. It would be like trying to feed an entire family on a single Big Mac.”
Over a three-year period, researchers radio-collared more than 100 pronghorn fawns in areas with no wolves and areas with large wolf populations in Grand Teton National Park, part of the Greater Yellowstone Ecosystem. As they monitored the fawns’ survival throughout the summer, the researchers found that only 10 percent of the young antelope survived in areas that lacked wolves but had higher densities of coyotes. In areas where wolves were abundant, 34 percent of the fawns survived. Wolves reduce coyote numbers by killing them outright and by causing them to relocate out of the Park’s wolf territories.
While pronghorn are not endangered, the population that summers in Grand Teton National Park had been reduced to fewer than 200 animals in recent years. Since wolves were reintroduced in 1995, the Grand Teton pronghorn have increased by approximately 50 percent. These pronghorn migrate more than 200 miles roundtrip, farther than any land mammal in the lower 48 states. WCS has called for permanent protection of their migration corridor, known as Path of the Pronghorn, to prevent the animals from going extinct in the Park. Representatives from the National Park Service, U.S. Fish and Wildlife Service, and U.S. Forest Service recently pledged support for protecting the corridor.
“This study shows just how complex relationships between predators and their prey can be,” said Berger. “It’s an important reminder that we often don’t understand ecosystems nearly as well as we think we do, and that our efforts to manipulate them can have unexpected consequences.”