Wolves lose predatory edge in mid-life

MINNEAPOLIS, Oct. 28 (UPI) -- A University of Minnesota study has determined the ability of Yellowstone National Park wolves to kill prey peaks when they are two to three years of age.

That finding challenges a long-held theory that wolves remain successful predators for their entire adult lives, researcher Dan MacNulty, who led the study, said. MacNulty said his research suggests wolves, who lived to be nearly six years old, are at top physical shape for only about 25 percent of their lives and that physiology can limit predation.

"Wolves are not perfect predators," MacNulty said. "They lack physical characteristics to kill prey swiftly, so they rely on athletic ability and endurance, which diminishes with age. They're like 100-meter sprinters -- they need to be in top condition to perform."

The research that included Douglas Smith and Daniel Stahler of the Yellowstone Center for Resources, John Vucetich of Michigan Technological University, David Mech from the U.S. Geological Survey and Craig Packer of the University of Minnesota is to appear in the December issue of the journal Ecology Letters.