A Fighting Chance for Antelope Island's Bighorn Sheep

Wading through Antelope Island’s chest-high stalks of yellow-blossomed mullein and gazing out across the shifting, sun-washed colors of the Great Salt Lake, you can almost trick yourself into believing you’ve stumbled into an impossibly remote, exotic land. But the clockwork roar of jet engines departing nearby Salt Lake International repeatedly intrudes upon your thoughts – a rude reminder of your proximity to Utah’s bustling Wasatch Front.

Still, the island, with its distinctive rock formations, flora and fauna, has a timeless, ethereal quality. In this tranquil refuge, Utah State University doctoral student Amanda Murray rises each morning from a tiny travel trailer sans plumbing and wrestles a “Bison Bronco” – a battered four-wheel drive Ford borrowed from the Utah Division of State Parks and Recreation – over boulder-covered trails into Antelope’s upper reaches.

 

About nine months into a three-year study, Murray, a S. J. and Jessie E. Quinney Ph.D. Fellowship recipient in USU’s Department of Wildland Resources, hikes six to 10 miles per day and keeps a solitary vigil. Perched at vistas along the island’s craggy, western ridges from dawn to dusk, the wildlife biologist observes some of the island’s most elusive inhabitants – bighorn sheep.

 

About ten years ago, the Utah Division of Wildlife Resources introduced California bighorn sheep, drawn from herds in British Columbia and Nevada, to Antelope Island. An ideal oasis, it seems, to protect the animals from human-introduced threats and create a thriving nursery herd to replenish areas throughout the West.

 

Using a spotting scope, Murray meticulously records the animals’ daily “activity budget” – grazing, sparring, scratching a rump on a rock; lifting heads in sudden, startled unison. She collects fecal samples from the animals, which she sends to a lab for analysis.

 

“The droppings yield a wealth of information,” she says. “We can quantify the animal’s stress hormones, examine the effect stress has on their immune systems, determine which ewes are pregnant and more.” 

 

Though the island’s bighorns are not endangered, the species has a precarious history in the Rocky Mountain West.

 

“The sheep nearly disappeared from Utah by the 1960s,” Murray says.

 

Overhunting, disease and fragmentation of the ovines’ habitat by urbanization and highways led to their decline, she says.

 

The Antelope Island experiment has proved successful and, periodically, animals from the growing herd need to be relocated. Though necessary as a conservation practice, Murray says, translocation doesn’t come cheap – either in terms of the cost of physically moving the sheep – about $1,000 per animal – or the impact on the animals’ health.

 

She likens the process of moving an animal to an organ transplant. “Relocation is necessary to maintain genetic diversity, health and survival of the species, but the stress on the animals is high,” she says. “The risks are tremendous and you want to ensure the best possible outcome.”

 

The island’s secluded nursery presents yet another challenge for the sheep once they venture into the outside world. The island has no cougars.

 

True, mountain lions are natural predators of sheep and a certain number of bighorns are expected to provide sustenance for the hungry cats. “But if they don’t have an innate fear or knowledge of predators, relocated sheep can become an instant feast,” Murray says.

 

Her research, funded by the Utah chapter of the Foundation for North American Wild Sheep, involves observing individual variations in sheep, including anti-predator behavior.

 

Murray’s work paves the way for continuing study that could one day allow biologists to identify sheep lacking anti-predator behavior and develop anti-predator cues to teach the animals to fear predators. For now, her research focuses on identifying the class of animals within a source population that is most successful in a translocation operation.

 

While the research Murray’s pursuing seeks to offer the sheep a fighting chance against translocation stress and predation pressure, resulting practices could benefit the lions. Restoring predator-savvy sheep to their former ranges could reduce the need for shooting of ‘problem’ cougars in release areas.

 

Prized trophy animals, bighorns fetch steeply priced hunting tags. Most Western states control hunting through the sale of lottery-issued tags and conservation permits. Conservation tags in some states may command as much as $250,000, while such permits for Utah’s sheep typically bring in about $20,000 to $40,000. Nearly 100 percent of the proceeds from conservation permit sales fund conservation efforts and research to ensure the survival of bighorn sheep.

 

Murray’s research has direct application not only to bighorn conservation in the American West but also in areas around the world where relocation of big game is part of conservation efforts, says Johan du Toit, USU Wildland Resources Department head, director of the USU-led Berryman Institute and Murray’s faculty mentor. In addition, he says, it has application to the livestock industry, which is continually seeking ways to reduce losses to predation.

 

Ultimately, Murray says, the bighorns’ survival depends upon their behavior.

 

“Our goal is learn more about these animals and to find the recipe for successful translocation that will allow the animals to thrive in a rapidly changing environment,” she says.

 

 

 

 

Contact: Amanda Murray [almurray@cc.usu.edu], 435-760-6971
Writer: Mary-Ann Muffoletto [maryann.muffoletto@usu.edu], 435-797-1429