CORVALLIS, Ore., July 21 (UPI) -- Introducing wolves to a test site in Scotland would establish a model for controlling the over-population of red deer, scientists in Oregon said.

SAN MATEO, Calif., June 22 (UPI) -- More large predators such as cougars are needed in wild lands in the western United States to enhance overall wildlife populations, two scientists say.

CORVALLIS, Ore., May 3 (UPI) -- Scientists said the disappearance of cougars from Yosemite National Park in the 20th century disrupted the entire ecology of the valley.

CORVALLIS, Ore., July 27 (UPI) -- U.S. researchers said the return of wolves to Yellowstone National Park has allowed aspen trees to grow there for the first time in decades.

BOULDER, Colo., Feb. 23 (UPI) -- A series by UPI examining the relationship of humans to the environment. This week: Despite its longstanding bad reputation, wolves can work some wonders on local ecosystems.