Rocky Mountain Bighorn Sheep
Submitted by Lois Ports for Bristlecone Audubon photos by Lois Ports
This January the lack of large amounts of snow in the Ruby Mountains made it possible to easily drive up the road in Lamoille Canyon. Many people enjoyed going to look for the Rocky Mountain Bighorn Sheep that can often be found in the lower sections of the canyon on the south facing slopes during the winter.
Bighorn sheep are the biggest members North America’s sheep family. Nevada has three distinct subspecies of bighorn sheep. Southern Nevada is home to the Desert Bighorn Sheep which is not as bulky and stocky. The Sierra Nevada is home to the California Bighorn Sheep and the Rocky Mountain Bighorn are found here in Elko County.
A large male (ram) can weigh up to 300 pounds and be 3 feet tall at the shoulder. The female (ewe) is roughly half that size. Bighorn sheep are grayish brown to dark brown in color with white patches on their rump, muzzle and back of legs. They tend to blend into the rocks in the rocky habitats that they prefer to inhabit. It is their white rumps that typically are seen first. Their winter coats are thick, double-layered and are often lighter in color. Bighorn sheep shed these heavy coats in the summer. They are specially adapted to detect dangers at great distances. Their eyes are wide set on their heads which allows for a greater field of vision. They have sharp hearing and a keen sense of smell.
The bighorn sheep’s hooves are made of two parts which allow them to cling firmly to steep and rocky terrain. The hooves are spongy in the center with a hard outer edge. The padded, soft, rubbery soles help them maintain traction and balance as they move up sheer rock faces and through the uneven and slippery ground. The pad of a bighorn sheep feels like a human heel and digs into the terrain, molding to the surroundings and helping the bighorn grip. The toenail-like outer hoof snags any slight protrusion in the rock face allowing the bighorn to grip on smaller surfaces.
Bighorn sheep have true horns that they retain throughout their life. Rams have large horns that curl around their faces by eight years of age. These horns can weigh up to 30 pounds. Females have smaller horns that curve slightly to a sharp point within the first four years of life. Mating occurs in the fall when rams use their horns as weapons of battle to fight for dominance or female mating rights. During the rut rams face each other, rear up on hind legs and pitch forward at speeds up to 40 mph. The loud crash of horns signals contact and can be heard up to one mile away. This ritual is repeated until one animal concedes and walks away. Bighorn sheep skulls are thick and bony to absorb this repeated impact with little physical injury to the ram.
These sheep live in single-sex groups during spring and summer migrating less than 20 miles seasonally. Males leave their mother’s group at about two years of age. The herd will move to higher elevations in the spring and summer. In late fall they retreat from heavy snowpack to lower elevations. During the winter they will come together and form a larger herd. Each young sheep learns a migratory route by following an older group member. Home ranges are thus inherited.
These sheep graze on grasses, sedges, and clover in warmer months and willow, holly, cactus, and sage in the cooler months. Their digestive system acts as a survival mechanism. A complex, four-part stomach allows sheep to gain needed nutrients from hard, dry forage. They eat large amounts of vegetation quickly and then retreat to cliffs or ledges where they can thoroughly rechew and digest their food away from possible predators. Bighorn Sheep can go without drinking water for months at a time because they get all the necessary liquids and minerals from the plants that they eat. They will also seek minerals at natural salt licks. The lifespan of bighorn sheep is approximately 10 years.
Historically, Rocky Mountain Bighorn Sheep were known to be in most of the mountain ranges of Nevada. According to E. Raymond Hall in Mammals of Nevada the Rocky Mountain Bighorn Sheep were considered extirpated from Elko County by the 1920’s. Three individuals were recorded near Verdi Lake in October 1921. By the 1940’s and well into the 1960’s there would be occasional rare sightings. In 1989 the Nevada Department of Wildlife transplanted 20 sheep from Alberta, Canada into the Ruby Mountains with an additional 25 in 1990. The East Humboldt Mountains received 31 sheep in 1992. By 1995 the population was estimated to be 160 sheep in the North Ruby Mountains. But up to 90% of that population died in an outbreak of disease in 1995-96. They were slowly repopulating again by 2009 when pneumonia began to decimate the population once again. Since the populations in both the East Humbolt Mountains and Ruby Mountains were exposed to the same pathogens, it was decided to depopulate the East Humboldt Mountains in 2012. The 17 captured sheep including 13 ewes were moved into Lamoille Canyon. February of 2013 the Angel Lake area in the East Humboldt Mountains received 20 (17 ewes and 3 rams) sheep again from Alberta. According to Scott Roberts from Nevada Department of Wildlife the population is increasing again according to the established management plan. The older ewes are now being replaced naturally by younger offspring. As of 2023 the arial surveys of the Ruby Mountains found 70 sheep and an additional 40 were living in the East Humboldt Mountains. It is efforts by NDOW, the Elko Big Horn Sheep Unlimited and concerned individuals in our area that help maintain these two populations of sheep.
To learn more about our area’s birds, plants and other wildlife follow us on FaceBook at Bristlecone Audubon. Contact us at [email protected] if you would like to receive our digital newsletter. Our next meeting will be on Tuesday, February 6, 2024 at 7:00 pm in the conference room at the Nevada Department of Wildlife headquarters (60 Youth Center Road, Elko, NV, use the side door). The program will be on Ocelot Conservation. Hilary Swarts, manager of Ruby Lake National Wildlife Refuge will share the research she did on these fascinating animals while she was in deep south Texas.