Colorado Parks and Wildlife biologists, wildlife officers and more than 40 staff members and trained volunteers spread across Pikes Peak in the pre-dawn hours on July 25 and Aug. 5 for an annual survey of one of Colorado’s most recognizable wildlife populations — bighorn sheep.

The Pikes Peak herd is a native, self-sustaining population. With its range spanning from Pikes Peak to Dome Rock, these are Teller County’s most photographed celebrities and one of the most visible bighorn sheep herds in the state. Thousands of visitors see the animals each year.

Decades of monitoring have provided CPW with a valuable record of population changes. The annual counts provide biologists with critical data on the herd’s size, composition and long-term health while giving observers a closer look at how the population is responding to an ongoing respiratory disease outbreak.

These bighorn surveys begin in the pre-dawn hours when the herd is most active. Observers disperse along 10 established survey routes. Some require hikes to remote observation points while other locations are along the Pikes Peak Highway. Using binoculars and spotting scopes, teams scan cliffs, alpine slopes and drainages, recording the location, movement, sex and age of individual sheep as well as noting any visible signs of illness.

Conducting surveys on two separate days helps account for weather, animal movement and other factors that can affect what observers see at any one time. Biologists combine the observations from both days to develop an annual population estimate.

The surveys aggregate statistics on the number of rams, ewes, lambs and yearlings and the corresponding ratios of those groups. Those figures, when compared with decades of data, help wildlife officials identify population trends, evaluate herd health and develop future management recommendations.

Respiratory disease, particularly pneumonia, remains one of the major challenges facing Colorado’s bighorn sheep populations. Officials say the disease is caused by combinations of respiratory pathogens that can spread through contact between infected animals.

On Pikes Peak, the effects have been especially concerning among lambs. Ty Woodward, the regional terrestrial biologist with CPW, said lambs can appear healthy and energetic early in the summer. As the season progresses, however, some begin showing signs of illness, including lethargy, lowered ears, reduced activity and eventually a deep cough which often escalates to respiratory distress and death.

Many infected lambs do not survive the winter, resulting in a significant loss of young animals before they can become yearlings and join the breeding population.

Wildlife officials first became concerned about the current disease problem around 2021 and 2022. At a nursery area on the west side of Pikes Peak, biologists observed ewes with lambs early in the season. By late September, however, they counted 19 ewes and no remaining lambs.

That prompted officials to collect samples and work with Colorado Parks and Wildlife’s wildlife health laboratory and researchers at Colorado State University to identify the pathogens involved.

“Every sheep count gives us another piece of the story, but this year we’re especially interested in what the younger animals can tell us about where this herd is headed,” said Woodward. “We’re hopeful the data will show more young females recruited into the population because that’s one of the clearest signs the herd may be starting to recover.”

The disease is not limited to Pikes Peak. Respiratory outbreaks have occurred across multiple bighorn sheep herds with movement between herds contributing to transmission.

“We’re working with researchers out of Colorado State University and in our wildlife health lab to do a lot of research on these pathogens currently to see if we can find some way of getting ahead of the curve,” Woodward said.