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Tracking the BighornsExplore more photos from the story |
As the five of us hiked around Rising Wolf Mountain, a monolith of ice-chewed rock in the southeast corner of Glacier National Park, we could hear clinking and rattling somewhere in the talus slopes above us—miniature rock slides unleashed by hooves. Kim Keating, a wildlife biologist with the Northern Rocky Mountain Science Center in Bozeman, Montana, was in the lead. He has studied Glacier's bighorn sheep for two decades, collaring 99 since 2002 and tracking them with GPS recorders and radio telemetry. The tranquilizer dart he carried had enough of the narcotic carfentanil and the sedative xylazine to pacify a 300-pound sheep. Because the dose is lethal to humans, Keating—and only Keating—would handle the dart.
The low-angled autumn sun lit up yellowing larch trees like candles. Stephanie Schmitz—one of three fieldworkers assisting Keating—spotted a small herd of bighorn in a golden meadow up ahead. Keating loaded his dart rifle, then began edging toward the animals. They raised their heads. Keating stopped, pretending to be doing nothing. He sat down for a few minutes. "To avoid startling them, you want the sheep to see you," he explained later, "but you have to be willing to walk away if the shot isn't right."
The sheep dropped their heads to munch on grass. Keating crept into shooting range—20 yards away or less—aimed and fired. A few sheep ran; some stared, befuddled. A ewe staggered.
The crew's first job was to prevent the ewe from tumbling downhill. "If they get going, they'll roll to the bottom of the mountain," Keating said. Assistant Josh Brown blindfolded the groggy animal, holding her head erect by the horns. Keating collected a snip of hair, a vial of blood and a swab of saliva. He counted two growth rings on her horn: she was 2 1/2 years old. Collar number 118, affixed with a radio transmitter and a GPS recording unit, was cinched around her neck. Keating injected the ewe with a drug to bring her out of her stupor. After a few wobbly steps, she ambled off to join the herd.
Bighorn sheep, Ovis canadensis, are a majestic symbol of the mountainous West. They browse at high altitudes and in steep, rocky areas from Texas to British Columbia. Rams' horns curl around their eyes and grow up to 45 inches long. Males butt horns to establish dominance during the fall rut. Ewes sport shorter, spiked horns similar to a mountain goat's. From their first days of life, bighorns are sure-footed enough to scale cliffs too steep for most predators to follow.
Two centuries ago, an estimated 1.5 million to 2 million bighorn sheep lived in North America; today, a mere 28,000 remain. Diseases caught from domestic sheep, competition from livestock for forage, and trophy hunting for their horns caused populations to plummet. Bighorns graze in mountain meadows, habitat that is being lost to expanding forests, which are growing beyond their historic boundaries in part because the wildfires that used to hold them in check have been suppressed. Glacier National Park, home to 400 to 600 bighorn sheep, lists the animal as a "species of concern," that is, at risk of becoming endangered.
To protect bighorns, Keating says, we have to understand them better. That's his mission. Each battery-powered GPS unit records the animal's location every five hours for a year. Then, on a programmed day, the collar drops off; Keating must go find it. "Retrieving a collar with its 1,600 or more stored location points is like Christmas," Keating said. "You never know what you'll find."
In the past few years Keating's collars have recorded a great deal of new information about bighorn behavior in the park, including previously unknown wintering, rutting and lambing sites. The devices have shown that bighorns travel greater distances, up to 20 miles, and visit mineral licks more often than researchers realized. The work has also revealed just how sheep-like bighorns can be. That is, they're creatures of habit. "They seldom explore new habitat," Keating says. They travel to and from their ranges for wintering, lambing and browsing along paths used by the herd for generations.
Comments
Kudos to these folks who are so dedicated! I lived in SD for many years and traveled on several occasions to Glacier Park and surrounding areas. We had a few Bighorn Sheep in the Black Hills (South Dakota) also. They are just fascinating to watch, especially if you can observe them for more than a few minutes. Watching the little ones climb is wonderous. They bounce up the rocks like they had springs attached to their hooves. Keep up the great work and thank you!
Posted by C. M. Meyer on March 3,2008 | 05:34AM