August 12, 2009

Water dispensaries keep mountain bighorn sheep alive

The Kerr Drinker. George Sutton peers into one of the two 1,600-gallon water collection tanks in the Old Dad Range of the Mojave National Preserve, which are filled by members of the Society for the Conservation of Bighorn Sheep. The group spends hours each month maintaining and repairing the tanks for sheep in the summer. (Mark Zaleski/The Press-Enterprise)

The Press-Enterprise

A herd of desert bighorn sheep deftly scramble up a rocky hillside in the Mojave National Preserve as the rumble of approaching trucks breaks the silence.

The pickups, each hauling plastic tanks filled with water, come to a stop in a cloud of dust. Soon, the drivers stretch fire hoses from the truck to two big holding tanks that feed a manmade watering hole -- a lifeline for the bighorn and other wildlife that lay claim to this inhospitable landscape.

There are 72 "drinkers" built and maintained across the desert from Interstate 10 north to Death Valley by volunteers with the Society for the Conservation of Bighorn Sheep. The group is a mix of conservationists and hunters whose efforts started 50 years ago when the founders began helping the struggling sheep population.

The work has grown more critical in recent years, they say, as desert springs dry up from drought and from a dropping water table as supplies are siphoned away by development in outlying areas.

"The sheep live on these drinkers from June to September," said Gary Thomas, 70, of Upland, who monitors and fills the watering holes. "Ideally, they would be naturally replenished (with rainfall), but that hasn't happened."

And so the group has resorted to trucking in water during summer months when the moist, green vegetation that sustains bighorn the rest of the year dries up.

In extreme cases, members pay for helicopters to haul water to the most remote locations and have hand-carried water in five-gallon bottles to areas where vehicle access is prohibited. Earlier this summer, the Forest Service donated use of its chopper to ferry supplies and sheep society members nine miles into an inaccessible area of the Santa Rosa Mountains south of Palm Springs to rebuild a drinker.

Threats to desert bighorn go beyond water shortages, however.

The elusive animals historically have been compromised by disease, hunting, habitat loss, competition with livestock and fragmentation of their ranges by fences, highways and canals that cut off wildlife passages between mountains, said Conrad Jones, a wildlife biologist and desert water coordinator for the state Department of Fish and Game.

Conservationists fear the onslaught of alternative energy developments that they say will denude the land and further impede the animals' movement.

The sheep need to travel between ranges and other herds to prevent in-breeding, keeping the animals more resilient to environmental extremes.

Dwindling rainfall is a concern. A 2004 UC Berkeley study found that rain levels have decreased about 20 percent in the Southwest during the past century and cited predictions that precipitation will drop another 10 to 20 percent by 2100. In that case, fewer lambs would survive because of less vegetation, the researchers found.

Desert bighorn in the peninsular ranges -- the Santa Rosa and San Jacinto mountains and Anza-Borrego Desert State Park -- are on the federal endangered species list. The isolated populations there plummeted from an estimated 1,170 in 1971 to about 230 when it was listed in 1998; now there are about 800, said Jane Hendron, spokeswoman for the U.S. Fish and Wildlife Service office in Carlsbad.

In all, an estimated 3,500 to 5,500 desert bighorn sheep live in California, up from fewer than 2,000 in the 1960s and '70s, Thomas said.

"Now we have a viable population," he said. "That's directly related to building big-game drinkers."

Bighorn sheep watch as members of the Society for the Conservation of Bighorn Sheep drive water to the Kerr Drinker at the Old Dad Mountain range in the Mojave National Preserve. (Mark Zaleski/The Press-Enterprise)

Limited range

After an early stop in Baker to take on 2,300 gallons of water donated by the local Community Services District followed by a 15-mile drive on a rough dirt track, the volunteers prepare to refill the Kerr drinker near Old Dad Peak, home to one of the Mojave's healthiest herds. The watering place south of Baker is named for Chuck Kerr, a society founding member whose son George continues his work.

Above the drinker, vultures circle over the spot where two camouflaged water tanks are nestled in a ravine. The volunteers spot a ram, its horns curled like an old toenail, lying motionless near a small stainless trough.

The animal is about 10 years old, almost the end of its life span, and has probably been dead a couple weeks, says George Kerr, a Fish and Game commissioner for Ventura County.

"A lot of times rams will find a place they know" when they are ready to die, he says. "It could be habitat stress."

At least nine bighorn with their characteristic white rumps keep watch from the canyon's rocky slopes. Sheep aren't the only wildlife that benefit from this water; golden eagles, badgers, bobcats, coyotes, skunk, deer, birds and bees also drink here.

When the group built this guzzler in 1985, they formed a dam at the bottom of the slope to catch rainwater and ran pipe from there to holding tanks. The tanks feed the stainless trough, intentionally small to reduce evaporation.

The society knows when the Kerr drinker needs filling, because a solar-powered sensor on the tank transmits water levels daily via satellite. The remote monitoring is one of the many advances the group has made.

In several sites, including the Ord, Newberry and Rodman mountains, battery-powered, infrared cameras track the number of animals visiting the drinkers. The information, combined with helicopter survey results, gauges population density.

"A sheep will not tend to stray more than two to three miles during the heat of the summer from one of these drinkers," said Jones, the Fish and Game biologist who helps on re-fill missions.

Another group, Desert Wildlife Unlimited in Brawley, has installed and maintains more than 120 drinkers from Interstate 10 to the Mexican border. That means there are less than 200 drinkers south of Bishop, Jones said. "That's not much."

Thomas said thousands of guzzlers would be ideal.

There is controversy

The conservation groups use money from grants, membership and fundraisers to pay to build the drinkers, which cost from $15,000 to $40,000. Refilling them costs about $1,000 per trip.

Jones called the volunteer groups a critical element in bighorn survival, citing a study published this year by U.S. Geological Survey scientist Kathleen Longshore, who found a correlation between artificial water sources and survival of the remaining bighorn populations in Joshua Tree National Park.

But such water developments are not without controversy. Some environmentalists say the drinking holes can spread disease and provide easy access to wildlife by predators.

Thomas, of the sheep society, said their 3-month-old camera monitoring program has not captured any mountain lions, the bighorn's main predator, attacking the animals at watering holes.

Joshua Tree resident Elden Hughes, a member of the Sierra Club's California/Nevada Desert Committee, opposes guzzlers because of their impact on pristine areas.

"They are usually putting them in wilderness areas, which means putting in a road and construction in wilderness. Those two are enough for me to oppose it," Hughes said.

Desert protection laws have made it more difficult to access many guzzlers, and the groups must get permits to drive into restricted areas. The sheep society builds two new drinkers a year, said Steve Marschke, the group's president.

Mike Smith, left, and Steve Marschke, of the Society for the Conservation of Bighorn Sheep, carry several fire hoses up to the Kerr Drinker in the Old Dad Range in the Mojave National Preserve. (Mark Zaleski/The Press-Enterprise)

Hughes also objects to drinkers as a way to increase bighorn herds for hunting. Fish and Game issues a limited number of hunting permits based on the count of older rams, which are not crucial to the herd. The endangered populations are not hunted.

Proceeds from permit sales are dedicated to sheep work, including biologists and programs to collar, capture and relocate animals to areas where they have historically lived and to increase genetic diversity among other herds.

Many relocated sheep come from Old Dad Peak, where the sheep society wraps up its most recent refilling project at the end of a nine-hour day. Hot and dirty, they head home.

Despite the back-breaking labor and disputes about the benefits, Thomas vows to continue his work.

"We've manipulated the environment almost everywhere, so we now have to continue to manage it. You can't just sit back and say we're going to let it go back to nature, now that we have isolated them into tiny islands with highways," he said. "If you don't, they will disappear."