Wild Bighorn Sheep in Yellowstone

Majestic. Regal. These are words that have been used to define the Rocky Mountain bighorn sheep. The first time you see a full-curl bighorn ram, you’ll be bound to agree. Of all the animals in Yellowstone National Park, the bighorn sheep embodies the spirit of high wild places.

Bighorn sheep (Ovis canadensis) once were found from the rough edges of the great plains to the far west and numbered in the millions.There are four main species of wild sheep found in North America including the Dall in Alaska and the Yukon, the Stone of British Columbia and the desert bighorn of the Southwest. The Rocky Mountain bighorn sheep is found from Alberta south to northern Arizona.

In the area that is now Yellowstone National Park, an entire race of people known as Sheepeater Indians devoted their lives to hunting bighorn sheep in the tall mountains, living year-round in the high country of Yellowstone and setting up elaborate traps along mountain ridges. These Indians often traveled in small family groups and are thought by some to be closely related to the Shoshone Indians.

The famed trapper Osborne Russell, who left the best account of early-day life in the Yellowstone country in a book called Journal of a Trapper, wrote of seeing thousands of sheep in the high country and in lower canyons of the mountain West. He and his companions camped during the winter of 1839 in the Snake River Canyon near Jackson, killing and eating mountain sheep.

“It is an exercise which gives vigor health and appetite to a hunter to shoulder his rifle at daybreak on a cold clear morning and wind his way up a rugged mountain,” wrote Russell, who admitted that during the chase, he was so focused on hunting that he felt little of the danger of the sport. Although he crept over steep slopes and nearly dangled off of cliffs, sometimes chopping steps with his butcher knife, he didn’t think much of it until he was back in camp that night. Then, he admitted, that the thoughts of the day’s adventures made his blood run cold.

Russell and fellow mountain men thought that bighorn sheep meat was among the finest of all fare, and so did countless others who followed in their footsteps. In fact, so many thought so highly of bighorn sheep mutton, that the animal was nearly wiped out.

Less than a century later, the naturalist-hunter-ranger William Marshall Rush, who spent much time in the Yellowstone backcountry, recounted a hunt in 1913. On that hunt, Rush and his companions had wound their way into the tallest and most remote country they could find, when they discovered a mountain ram. Rush, though in the lead and with the opportunity to shoot the ram, just watched him. But one of his companions unlimbered a rifle and felled the majestic sheep. Later, when Rush and his comrades were dining on mutton around the campfire, he was asked why he didn’t kill the ram when he had such a good chance to do so. Wrote Rush in his book, Wild Animals of the Rockies:

“Just trying to give him a break,” I said with some bitterness. “Do any of you realize that yesterday was the last day of the last open season on mountain sheep in Montana? There will never be another chance to shoot sheep in this state.”

Fortunately, Rush’s prophecy proved to be false, and today, the states of Montana, Wyoming and Idaho support good numbers of wild sheep and goats, though hunting is very restricted. But mountain sheep will probably never be found in the numbers that Russell enjoyed.

In Yellowstone, bighorn sheep occupy rough, tall country where they have good escape routes from predators. According to the Park Service, there are fewer than 500 bighorn sheep in all of the park, with about 250 in the northern range. Specimen Ridge, Mt. Washburn and Mt. Everts are all good places for mountain sheep.

One of the primary problems with the recovery of bighorn sheep numbers is their susceptibility to disease. In the 1980s, a disease known as pinkeye felled many sheep, and other diseases and parasites take sheep each year. Indeed, disease may have accounted for far more loss of wild sheep than over-hunting.

In the early days of the West, the domestic sheep industry was a growing concern, and when domestic sheep mingled with wild sheep, the wild sheep almost always came out on the short end. Domestic sheep easily transmit diseases to wild sheep, dooming wild native populations. Pneumonia, lung-worm and mineral deficiencies are all causes of bighorn sheep losses.

Today, the sheep industry in this country has been out-produced by foreign markets such as Australia and New Zealand.

For North American wild sheep, this is good news. In many places, wild sheep are making a comeback thanks to wildlife managers who are transplanting populations of bighorns into historic ranges that have been abandoned by domestic sheep producers.

In appearance, stature and agility, the bighorn sheep is a far cry from his domestic cousin. Bighorn sheep don’t have wool; in fact their coat is more like that of a deer than a domestic sheep. They are also extremely agile animals, using rough country for hiding and escape cover from predators.

Bighorn rams can weigh about 300 pounds, while the ewes are around 200 pounds. Since bighorns occupy high, rough country, they are very adept at eluding predators. Such predators as bears and wolves have little effect on mountain sheep, but golden eagles are efficient predators of young lambs. In Wild Animals of the Rockies, Rush recounted seeing a golden eagle take a lamb to feed its young in a cliff-side nest.

In November or December, the bighorns enter the mating season. At this time, the sheep get into spectacular fights, where they clash their horns together, in a sparring match to determine dominance. Old rams often carry scars from these battles, and their horns are chipped from fighting. Rams will also rub the ends off their horns when they grow into their field of vision, an effect known as brooming. These horns have annual growth rings that can actually be counted to estimate a ram’s age. The ewes have horns too, but they are small and do not curve in the full sweep of the ram’s head gear.

Lambs are born in May or June and groups of ewes and lambs will band together and browse upon grasses and forbs in the high country. In the winter, bighorns can be found close to roads in such places as Gallatin Canyon, where they paw through snow in search of forage. Some very hardy bands of mountain sheep can spend the entire winter in high mountain holds, browsing on slopes that are swept clean of snow by strong winter winds.