The cougar connection.

Researchers who demonstrated the link between wolf reintroduction in Yellowstone and the park's subsequent ecological upswing have set their sights on another top predator, the cougars of Utah's Zion National Park. Oregon State University's William Ripple and Robert Beschta found that cougars, like wolves, signal a healthy ecosystem in Zion. But there's a problem: The notoriously reclusive cougars despise human company. In Zion Canyon, famed for its dramatic sandstone cliffs, 2.6 million visitors a year drive the big cats away.

The researchers studied Zion Canyon and North Creek, an adjacent backcountry area of the park that is accessed by a steep canyon trail. In North Creek they found so many toads, wildflowers, sedges and other vegetation that Ripple struggled to avoid crushing them as Beschta measured water depth. They also found cougar scat--evidence that some of the park's estimated 100 cats were present.

Zion Canyon was a different story: no cougars, no aster and cardinal flowers, and only one toad compared to the 150 they found in the backcountry. Other species followed the same pattern. Only mule deer, a favorite cougar meal, flourished, their overgrazing encouraging erosion.

While a shuttle system installed in 2000 has removed cars from the canyon--and an ensuing uptick in wildlife sightings by visitors demonstrates the shuttle's relative unobtrusiveness--Beschta thinks the park needs to make more changes to prevent further ecological damage. "If something can be done to alter the effects of deer, perhaps impacts to the ecosystem can be reversed," he says.

Cougars share another similarity with the wolves of the researchers' past studies. While they're protected inside the park, they are fair game for hunters in the surrounding area, and are loathed by ranchers.

Leon Lewis, who owns 100 acres south of the park, says he nearly lost two horses to cougar attacks, and his neighbors have lost goats, calves and pets. He added that the attacks had increased in recent years.

"The cougars have terrorized my animals for several years," Lewis says. "I'd like to see them eliminated from around here."

Neither Lewis nor the researchers has ever seen a cougar in the wild. Despite their starring role in the ecosystem, the shy big cats do most of their work out of the limelight. "I'm assuming they were watching us," says Ripple, "but we never had the opportunity to watch them."

CONTACT: The Leopold Project, [phone], www.forestry.oregonstate.edu/leopold.