Mountain Bighorns Waning-- or Hiding : Experts surveying San Gabriel range note a sharp decline in the herd. Skeptics say counting system is inexact.

Dick Conti remembers the day, about a decade ago, when a mere four hours of quietly sitting in a cold, windy canyon brought the ultimate reward: sighting a bighorn sheep scrambling 300 feet up the face of a sheer rock cliff.

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If only it were that easy now.

In March, the latest helicopter survey turned up only 60 bighorn sheep in the San Gabriel Mountains north of Glendora, down from 222 in 1992. In the 1980s, aerial counts found as many as 500 bighorns.

Wildlife experts, who have conducted an annual count of the elusive animals in the San Gabriel Mountains since 1976, are at a loss to explain what at first glance looks like a devastating decline.

So far, they say, there is no obvious evidence of disease or major changes in habitat that would account for the decline. Wildlife surveyors “rarely find such dramatic differences,” said Steve Torres, a wildlife biologist for the state Department of Fish and Game.

Still, he said, biologists want to proceed cautiously.

“I’m not sure I’d call it a devastating decline,” said Torres, a bighorn sheep specialist. “We’re concerned about it, and the warning flags are up.”

Other bighorn sheep observers also want more information to determine whether there is cause for alarm, whether the problem is with the counting system or whether the decline is part of the natural ebb and flow of any species. And they say that the species is in no danger of extinction.

“Even if we were to lose all the sheep in the San Gabriels, it would be a loss, but there are other herds of [bighorns] all around the state,” said Conti, who heads the Society for the Conservation of Bighorn Sheep, a volunteer group that monitors the animals.

The San Gabriel bighorn sheep herd traditionally has been the state’s largest. Statewide, biologists track 60 herds, a total of 4,600 bighorns. Bighorns, which are distantly related to domestic sheep, have huge, curly horns weighing up to 30 pounds. Their coat is not woolly but more the texture and color of deer fur.

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Maybe, Torres said, the numbers are down because officials did not do a good job of counting in the March survey. It is easy to miss bighorn sheep in the San Gabriels’ deep, chaparral-covered canyons during one count but then spot them grazing on open land in another count.

“It’s an inexact science,” Torres said. “It’s a bunch of scientists jumping in a helicopter.”

Loren Lutz, author of the 1988 book, “Bighorns of California,” said the aerial count is an unreliable indicator of the species’ health.

“I have some doubt about the ability of people to know what they’re looking at, how to count, where to count,” Lutz said.

This month, Fish and Game biologists will hire a researcher to study past sheep census data, including how and where the animals were counted, as well as habitat changes through satellite and other high-altitude photographs, Torres said. The photographs will help biologists determine whether pollution, weather and other elements have affected vegetation in sheep habitat.

Fish and Game administrators cannot take steps to protect the sheep until they get definitive data, Torres said. Even then, there is little they can do. Wildlife biologists, with U.S. Forest Service approval, could plan controlled burns to clear away thick brush for more open areas, where the sheep prefer to graze. Open space also gives the animals a better shot at spotting and avoiding predators, such as mountain lions.

Or officials could limit hiking on trails in the sheep habitat. Too much exposure to people, and sometimes their dogs, can be stressful and cause the sheep to move to outlying areas, where vegetation and water might be sparse.