After a brief pre-dawn gathering, over 40 volunteers and Colorado Parks and Wildlife staff split into teams Wednesday morning and headed off into the high alpine.

They were on an annual mission to count and catalog the bighorn sheep population of Pikes Peak, an effort that’s been ongoing since 1988. The volunteers gathered before sunrise to take advantage of the sheep’s most active hours — usually dawn and dusk.

Ken Anderson, a longtime CPW volunteer who regularly tracks the sheep throughout the year, was a key source of information for where they might be found.

Sometimes it takes a keen eye.

“All you’re seeing is rocks, and then a rock stands up,” he said.

This year, the team was taking special care to document an ongoing threat to the herd. For about five years, watchers have noticed high death rates among lambs stricken with pneumonia. Normally playful, a sick lamb will become lethargic and develop a rattling cough. By next spring, the lamb often won’t have survived to join the herd as a yearling.

“That’s hard to see,” said Ty Woodward, a CPW biologist.

Woodward said he hoped the count could help researchers understand how disease is affecting the herd. Once all the sightings are cataloged and checked for duplicates, he plans to pay extra attention to the number of yearlings and ewes in the population. Ewes are female sheep.

The origin of the Pikes Peak outbreak is difficult to pin down. One theory centers on a migratory sub-herd of sheep that descends the mountain to Dome Rock State Wildlife Area during birthing season.

“It’s somewhat unique, but it is also something that is a very fragile part of their existence,” said Woodward.

The biologist thinks the migratory group might have brought back disease when the mothers and their young gathered at the “nursery” near Devil’s Playground on the west side of the mountain. In 2021, observers saw a normal number of lambs and ewes at the beginning of summer. By fall, there were no more lambs.

Poor decisions by tourists on the mountain are worsening the situation.

“We’re seeing a lot of bad behavior, both by the sheep and the people,” Woodward said.

Bighorn sheep are spending more of their time and in higher numbers near the Pikes Peak Highway, encouraged when humans feed them. When more of the herd is concentrated in one place, the chances for disease spread increase.

“They congregate, and then in the fall they disperse. They go back to all the different parts of the mountain, and they take the bugs with them,” Woodward said.

The Pikes Peak bighorn sheep are not alone in battling lamb mortality from pneumonia: the disease has been identified as a major risk to populations statewide.

The herd on Pikes Peak is special for several reasons. It’s one of the most visible in the state, with thousands of visitors catching glimpses or up-close encounters. It’s also a priority population for CPW. While bighorn sheep have been reintroduced in many areas where the species lost ground in the 20th century, the Pikes Peak herd is endemic and has had few transplants.

“It’s definitely one of the prides of Colorado and prides of the state,” Woodward said of the species.