CPW studies Aspen-area elk herd to see how calves are faring

The Aspen Times

Pregnant cow elk were flying through the skies of the Roaring Fork Valley last week, but it wasn’t an alien abduction. It was the launch of a six-year study by Colorado Parks and Wildlife.

Wildlife officers and a contractor helicopter crew temporarily captured 24 pregnant elk in locations ranging from Sky Mountain Park outside of Snowmass Village to south of Glenwood Springs, CPW acting area wildlife manager Mike Yamashita said.

They were strapped into harnesses and transported to a staging area where their health was monitored and recorded. They were implanted with a transmitter that will drop out when they give birth this spring, he said.

The elk were flown back to where they were found or were released from the staging area, if it wasn’t far from where they were snared.

Once the cows give birth, wildlife officers will scramble to the sites to capture the newborn calves and fit them with collars or ear-tag transmitters so their travel patterns and survival rates can be studied, Yamashita said.

“It’s part of a project where we’re looking at elk recruitment issues,” he said.

Recruitment in this case means calves reaching the age of 1, when they are considered recruited into the herd.

CPW is interested in the study because the birth rates of several elk herds in the state are below what is considered sustainable. Similar research is occurring with herds in other parts of Colorado.

An elk herd needs a birth rate of 40 to 50 calves per 100 cows to be sustainable, Yamashita explained. The Avalanche Creek Elk Herd, the name given to several bands of elk that roam in the Roaring Fork Valley on the south side of Highway 82, has experienced ratios from 30 to the low teens per 100 cows over the past decade, according to estimates from aerial surveys conducted each year.

That has wildlife officers concerned, Yamashita said.

So, CPW wants to monitor what is happening with the calves — whether they achieve recruitment or the timing and cause of death.

The research will be carried out over six years to monitor elk under different conditions. Last year’s weather, for example, couldn’t be much more different than this year’s weather. The snowpack was rapidly disappearing last March. This year it is well above average. Conducting the research over six years will balance out environmental factors.

The overall results will help CPW determine if cows aren’t getting pregnant or if calves aren’t reaching recruitment.

“That’s one of the real questions we’re asking with this study,” Yamashita said.

To capture the pregnant cows, CPW uses fixed-wing spotter aircraft in the air to guide the helicopter crew.

They honed in on small batches of elk and fired nets to capture the cows. The elk were hobbled and blindfolded, then flown to a staging area where wildlife officers were waiting.

The cows’ health is closely monitored and they aren’t harmed during transport, Yamashita said.

The goal was to capture 30 pregnant cows in the Roaring Fork Valley. The contractor had captured 24 when it was called to a different project in Craig on Wednesday, Yamashita said. The hope is to return this year to capture six more cows for the research.

Cows were captured in the Owl Creek/Sky Mountain Park area, Wildcat Ranch, the Crown in the midvalley and between Carbondale and Glenwood Springs.

Roaring Fork Valley resident Dan Gageby had the good fortune of witnessing the crews capture the cow elk near the property where he works. He was able to get pictures of the process.

Most calves will be born toward the end of May. The amount of time officers will be in contact with calves to install collars will be “minimal” and not harmful, Yamashita said.

The study will show elk migration patterns, he said, and will help wildlife officers and public lands managers gauge if recreation is affecting recruitment.

Many public lands in the valley have winter closures to benefit wildlife. The Pitkin County open space program closes Sky Mountain Park and the Glassier Open Space, next to the Crown, from Dec. 1 through May 15.

In the Pitkin County Open Space and Trails department’s February newsletter, officials said a second part of the study will entail placing wildlife cameras in a grid pattern in select areas to observe elk and other wildlife. That also will help evaluate seasonal closures.

The open space program provided funds to help CPW conduct studies on elk, bighorn sheep and mountain goats. It budgeted $92,000 this year to purchase tracking equipment and another $54,000 contribution is being contemplated for 2020.

Once results of the study are in, they will be shared with public land managers, according to CPW.

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