SHEEP: Wildlife Is Monitored
Crook, Snoopy, Pancho and Lilly--more capable hounds you’ll not find--charge ahead, pursuing a mountain lion that knows this game well.
The last time the dogs were at its heels, the lion bolted up a tree. The trackers arrived and shot him with a tranquilizer dart. He fell from a branch, landed on his head and, while he lay in a daze, they fitted him with a radio collar. Then they turned him loose.
So now this cat wasn’t about to get himself treed.
The trackers forge on, huffing the thin air, pushing away shrubs, following a chorus of yelps that fills the morning sky. After four years, the signal from the collar is fading and that won’t do.
This lion, like all of the Eastern Sierra’s lions, must be watched. The region’s deer must also be watched, along with its bighorn sheep.
These animals are wild now in name only. They’re under a virtual microscope, with the resolution cranked to an unparalleled level.
Once, the three populations fluctuated according to natural cycles. As deer populations grew, so did the number of mountain lions. When deer herds thinned or fled, lions would eventually follow suit. Some would sustain themselves on sheep until deer became more plentiful.
Now, there is no room for error. Too few deer with too many lions could mean no more sheep. Man, who over the years has brought about a world of change, is compelled to take total control.
“One of the things we don’t want to do as wildlife managers is let it get to that point,” says Steve Torres, a California Department of Fish and Game biologist and an expert on large mammals. “But the reality is, we’re sometimes stuck with these kinds of situations....”
Few places have the kind of intensive wildlife management practiced in the Eastern Sierra.
The aim is to preserve Sierra Nevada bighorn sheep, a subspecies similar in appearance but genetically distinct from bighorn sheep found throughout western North America. Sierra Nevada bighorns once numbered as many as 1,000; a few years ago there were as few as 100 as they teetered on the brink of extinction.
Hunting took a sizable toll, until it was banned in 1878. The introduction of domestic sheep, which carried a respiratory bacteria, wiped out thousands of bighorns, including many of the Sierra Nevada variety.
That meant big trouble in the face of growing numbers of mountain lions.
A California bounty on cougars ended in 1963. Sport hunting was banned in 1972. Though mountain lions weren’t--and still aren’t--considered threatened or endangered, California voters in 1990 gave them “specially protected” status by passing Proposition 117, which made it illegal even for wildlife managers to kill them unless the animals threatened livestock or humans.
More cougars crawled back into the picture. And although they preyed primarily on deer, some had begun to “prey switch” to bighorns.
The sheep reacted by refusing to venture down out of the snow, to the warmth and bounty of their winter ranges. Their numbers plummeted.
On Jan. 3, 2000, the Sierra Nevada bighorns were declared an endangered species, and federal and state wildlife officials began an unrivaled restoration effort.
A team of 12 wildlife managers, operating with a 5-year funding package provided by the Legislature, is charged with conserving five herds scattered from Lone Pine to Lee Vining, and establishing seven others in suitable locations. This means collaring and constantly monitoring all of the mountain lions, closely watching mule deer herds, moving sheep to new locations and, perhaps, growing sheep in captivity for eventual release.
In an exception to Proposition 117, the wildlife managers have permission to kill mountain lions deemed an imminent threat to the Sierra Nevada bighorns. They’ve killed only three so far. Ultimately, they are in the business of balancing wild animal populations, and setting down parameters for similar management schemes in the future.
Says Vern Bleich, a Department of Fish and Game senior wildlife biologist and the project leader: “If we come out of this in 15 years and say we still have sheep and whacked 27 lions in the process but with no understanding of the way things work, then we’ve failed miserably.
“So the pragmatic end of it is: Save, conserve and restore sheep. The academic end of it is: Let’s try to understand the way things work so that in the future [wildlife] managers will have information to them, which we didn’t have.”
Looking for the Lion
Trackers Jeff Ostergard and Mike Morgan have caught up to the dogs, but have yet to close in on the lion with the aging collar. The cat’s territory is north of Crowley Lake and east of U.S. 395. The animal poses no imminent threat but could easily cross the highway and reach two areas holding bighorn sheep.
Supervising the effort from behind the wheel of her pickup is Becky Pierce, also a Department of Fish and Game biologist. Her trackers spend their days in the field, picking up signals from collars to pinpoint positions as best they can, and searching for signs of new lions.
Pierce is the one who decides when a lion has to be killed. Being fairly new to the sheep restoration project, it’s a call she has only had to make once. It involved a collared lion that continually staked out canyons used by sheep to reach their winter ranges.
The lion they’re after now is one of 11, from Lone Pine to Lee Vining, wearing radio collars that emit a signal detectable for a radius of 20 miles, depending on the terrain. Another is wearing a more advanced global positioning satellite collar.
“I can’t say that we have them all collared,” Pierce says. But all the new lion tracks they are spotting end up being from a marked, or collared animal, “so we probably have the majority.”
The cats are highly territorial and require plenty of space. These territories often overlap as they follow the migration of mule deer to and from their summer ranges on or even beyond the Sierra crest, to its western slope.
Pierce has found that just as deer numbers are governed by the availability of forage--mostly bitterbrush--lion numbers are governed primarily by the availability of deer. However, there’s a long time lag before lions adjust to changes in deer numbers.
She studied how deer in nearby Round Valley started to rebound in 1992 after the end of a prolonged drought that had knocked down the herd to about 900 animals.
Today, with the herd holding at about 2,500, mountain lions seem to be experiencing an upsurge as well.
As evidence, Pierce points in the direction of Wheeler Ridge, a prominent abutment to Round Valley. An adult female lion has staked out territory there, bringing with her 3-year-old juveniles.
“The whole time I did my work through the ‘90s I never had a female that brought three juveniles to this age--never,” Pierce says. “So that’s telling me that all of a sudden things are better for the lions.... “
The lion she is referring to has killed only deer. But she remains high on the watch list because Wheeler Ridge is the site of the largest bighorn population, more than 75 strong.
Foraging Animals
The day before the attempt to re-collar the mountain lion, three of the wildlife managers watch as an adult ewe traverses down a near-sheer cliff to forage in a meadow near Wheeler Ridge. Bighorn sheep, which spend their summers above the timberline, learn this precarious art early. With the ewe are a 2-year-old male and a lamb.
The sheep prefer the rocky, open terrain of the high country because they can use their keen eyesight to spot potential threats. But the low country beckons each spring; it is there that the lush grasses first begin to grow. But it is also there, beneath the craggy canyon stairways, that lions are most likely to wait in ambush.
One of the wildlife managers, John Wehausen, a University of California biologist and expert on Sierra Nevada bighorn, said he had witnessed an ambush only once. He was at the mouth of a canyon near Mt. Baxter and “saw a group of sheep running out of that canyon like they’d seen the devil,” he recalls. “And I saw this lion slinking around in the rocks.”
Most of the sheep turned and scurried well up the steepest slope. But a single ewe didn’t climb far enough. Wehausen watched as the cat, with a leap of about 25 feet, was on the ledge and with its jaws clamped on the neck of the sheep.
“It’s all he can do to hang on there on the ledge, but it’s total grace,” Wehausen says.
“He grabs her by the throat with his teeth and pulls this 120-pound ewe down off of the rocks,” he says.
That was in 1982, when most of the Sierra Nevada bighorn were at Mt. Baxter. Six years later, when the drought was knocking down Eastern Sierra deer herds, the number of lion kills of bighorn sheep had reached 49 in the Mt. Baxter area alone. Wildlife managers started killing cougars, one each year in 1988, ’89 and ’90 near the particularly besieged Lee Vining herd.
But then came Proposition 117, putting the guns of wildlife managers back on the racks.
The presence of lions at the lower elevations, Wehausen says, kept the sheep from visiting their traditional winter ranges. They were more content in the upper recesses of their harshly frigid high-mountain refuges, where food was scarce at best.
Ewes that avoided winter ranges, Wehausen found, lambed a month later than those that did not, and those lambs experienced a much lower survival rate. The heavy snows of 1995 and 1998 ravaged the herds, collectively leaving only about 100 animals.
The wildlife managers lobbied for and won the federal protection for the sheep. It provided the muscle to remove the remaining domestic sheep grazing allotments, eliminating that threat.
It reaffirmed the realization that much more needed to be learned if the Sierra Nevada bighorns, despite their sure-footed ways, were to keep from tumbling off the face of the earth.
Today, after successive mild winters, the drop in lion numbers and the selective removal of mountain lions at Lee Vining, Wheeler Ridge and Sawmill Canyon, bighorn number about 250.
Another census is underway. The fitting of collars and collection of data are ongoing. Sites for the establishment of new herds are being identified and the feasibility of a captive breeding program is being studied.
Elusive Target
Ostergard and Morgan eventually catch a glimpse of the cat with the faulty collar, passing through trees ahead on the trail, with the dogs in hot pursuit. Their high-pitch bawling indicates that the predator has been treed.
But suddenly the bawling stops and there is only the sound of the wind. With a leap and a bound, and with a fresh breath of air, the cat has again put himself ahead of the chase. The trackers corral the dogs for the day, but they’ll be back tomorrow. One way or another, the cougar will be caught.
