They Pulled the Wool Over Expert’s Eyes

The helicopter carrying John Wehausen swooped low over the Sierra Nevada in January, allowing the wildlife biologist to find his quarry: bighorn sheep perched atop a cliff in Kings Canyon National Park.

Wehausen was stunned. He had been studying bighorn in the Sierra for nearly three decades. But he had had no idea that this flock existed until a rock climber stumbled upon it in the summer of 2002.

So Wehausen and Fish and Game officials had chartered the flight to confirm the flock’s existence. Wehausen ultimately counted 16 bighorn. There were lambs among them -- a sign the flock was growing.

“I’m approaching 30 years working on Sierra sheep and, I have to tell you, my dream was to discover a new sheep population,” said Wehausen, who works for the University of California’s White Mountain Research Station.

“I pursued sightings for years. Government agencies gave me money to look for sheep. We had one that we thought existed north of Yosemite, but we certainly never documented one.”

The new flock was deep in the wilderness, in a landscape of high peaks and lakes known as Gardiner Basin, just a few miles from the park’s popular Cedar Grove area. Wehausen is one of the state’s foremost experts on bighorn and he’s not sure whether sheep had ever lived in this area or had ever before wandered this far west.

Populations of Sierra bighorn sheep dipped to historic lows in the late 1990s, when there were just 100 left in the entire range. That year the sheep were listed as endangered by the state and federal governments. Today, there are 300 and their numbers may be growing.

The population has doubled in Yosemite National Park in the last few years. And, those sheep are also expanding their range into areas where sheep haven’t been seen for years, according to Les Chow, a wildlife biologist with the United States Geological Survey.

Bighorn sheep were once found over much of the open country of the eastern Sierra, which offered plenty of grass to eat and easy escape routes to steep terrain where the sheep could be safe from predators.

In the 1800s, bighorn populations fell prey to hunters hired to feed hungry gold miners in the Sierra. About the same time, domestic sheep grazing in the mountains are believed to have passed a disease to the wild sheep, decimating many flocks.

A few hundred sheep managed to survive in the Sierra until the late 1970s. Then, as Wehausen said, things began to go “haywire.”

The problem in recent years, in his view, has to do with the changing relationships of mountain lions, deer and bighorn sheep.

In the 20th century, lions in the eastern Sierra are believed to have fed mostly on mule deer. But toward the end of the 1970s, mule deer numbers began plummeting, and the lions turned their attention to the sheep.

By the late 1990s, biologists were worried that there might be too few female sheep left for the population to rebound through reproduction. The state was even granted the power to kill three mountain lions -- which are protected from hunting -- to try to protect the sheep.

Then things changed.

Lion populations began falling, possibly because deer numbers were down. Sheep numbers began rising. Exactly how far the sheep population may expand is anyone’s guess, especially in light of evidence that lions are making a comeback.

That has left Wehausen trying to fathom the mysteries of an ecosystem where all of these animals once flourished. Why are deer numbers down? How did sheep, lions, deer and the Indians who hunted them interact before Europeans settled the area?

“These are dynamic systems,” Wehausen said. “What’s driving the dynamics is the big question.”

At this point, there are sheep in five distinct areas of the Sierra. There is historical evidence that sheep once were found in about 17 areas. Wehausen and Fish and Game officials worry that a population of 300 sheep still isn’t large enough to withstand problems such as prolonged drought, disease or possible increases in lion attacks.

“It was a pleasant surprise that there were sheep in there we weren’t aware of, but it wasn’t a total surprise, because this is big country and there could be sheep in other areas that we didn’t know about,” said Vern Bleich, the bighorn sheep recovery manager for Fish and Game.

“Things are more promising than they were, but we’re a long, long ways from being where we need to be,” Bleich said.

Wehausen is cautiously optimistic about the future of the Gardiner Basin herd.

“What they have found is probably a refuge free of mountain lions,” he said.

Seeing the sheep won’t be easy for most of the park’s visitors. It takes three to four days to backpack into Gardiner Basin and the trek involves a steep climb over at least one high mountain pass.

Not even Wehausen has seen the herd from the ground, although he’s eager to get back into the basin and to another secret spot in the Sierra where he thinks he may find more sheep.

“I’m good at finding sheep,” Wehausen said. “It’s my business.”