Bighorn sheep of Glenwood Canyon: past and present |

Bighorn sheep of Glenwood Canyon: past and present

Julie Mao and Phil Nyland

Rocky Mountain bighorn sheep are known for their large curling horns and athletic agility in steep, rugged terrain. Long before 1980, when construction of Interstate 70 began in Glenwood Canyon, bighorn sheep were found there. Information on this bighorn herd has been collected jointly by the United States Forest Service and Colorado Game, Fish and Parks Department (now Colorado Parks and Wildlife) as far back as 1948. This is a very long time in the context of the wildlife management profession. Science and technology have evolved light-years in this period from pen and paper to digital downloads.

And still, interest in bighorn sheep has persisted because these animals are charismatic and majestic. As Colorado’s state mammal, they are a symbol of the Rocky Mountains, and a ram is the emblem of Colorado Parks and Wildlife, or CPW. Photographers, hunters, tourists and local residents alike enjoy spotting bighorns in the canyon. Yet the species is so vulnerable that some professionals joke that bighorn sheep are made to die.

Why? Bacterial respiratory infections cause acute pneumonia in bighorn sheep, leading to rapid death of animals that are in otherwise good body condition. Outbreaks in bighorn herds can occur when bighorn sheep become infected, possibly after coming into contact with either domestic sheep (or less commonly, domestic goats or cattle) or other infected bighorn sheep. Following a major die-off, it can take many decades for a population to recover because bacteria can persist for years in the herd, and there is currently no vaccine or any practical treatment for these respiratory infections.

Other conservation issues are predation from mountain lions, vehicle collisions, and indirect threats from poor habitat condition, human disturbance, and displacement from foraging areas.

Currently there are 35-40 bighorns found in Glenwood Canyon and the rugged hillsides above Glenwood Springs, based on monitoring conducted by CPW, volunteers, and Forest Service personnel in cooperation with funding by Rocky Mountain Bighorn Society. The Glenwood herd has persisted, and even grown in recent years, despite individual cases of respiratory infection and one confirmed pneumonia death.

Nevertheless, a respiratory disease outbreak could occur unpredictably, causing a rapid population collapse, which has happened in herds elsewhere in Colorado and other western states. At present, wildlife disease researchers are working to find a treatment for respiratory infection, and the Forest Service is working to maintain or improve native habitat for bighorn sheep on White River National Forest. Robust habitat ensures adequate food and resting areas for bighorns so they can maintain good body condition to help fight off respiratory infections. Also in the event of a population decline, improving habitat in the long term would allow the herd to recover and to re-populate their range.

Bighorn sheep are highly visible along Glenwood Canyon’s bike path. They can be seen throughout the year, but especially during the fall rut (breeding period) and winter. For your safety and to protect the sheep, keep your distance and keep dogs on a leash.

You may see radio-collars equipped with GPS transmitters on bighorns in the canyon. Using this technology, state and federal agencies track seasonal movements, distribution and survival of individual bighorns. Monitoring data also helps track population trends of the herd, identify areas where habitat improvement projects would benefit sheep, and assess how the Forest Service can manage domestic livestock grazing where the bighorns range.

Yes, interest in Glenwood Canyon bighorn sheep has kept up. Perhaps it’s the majestic nature of these animals. Perhaps it’s the call of the canyon. Regardless, let’s hope these animals are found in the canyon long after today’s technology is a thing of the past.

Julie Mao is wildlife biologist for Colorado Parks and Wildlife Area 8, and Phil Nyland is wildlife biologist for the White River National Forest Aspen-Sopris Ranger District.

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