How’s life in Blue Sky Basin? |

How’s life in Blue Sky Basin?

Cliff Thompson
An aerial view of Vail Resorts Cat III ski expansion area taken on August 8, 1999, at Vail, Colo. (AP Photo, Vail Daily/Quentin Hunstad)

Predictions in the 1980s and “90s that development of Vail Mountain’s 885- acre Blue Ski Basin would devastate wildlife by bringing development to undisturbed mountain habitat may have been an overstatement of the facts, according to a couple of wildlife studies conducted in the area.

Since ski-area development ceased in 2001, there has been a change in the numbers of some animals and no little or no change in others, studies conducted over the last dozen years by a pair of Colorado State University wildlife biologist are showing.

Change in habitat- in the case of ski trails, from forest to meadow – as well as the added human presence seem to be defining factors.

Large animals

One study, which focused on deer and elk using the area for summer range and for fawning and calving, was conducted by Bill Alldredge, a former Colorado State University professor and wildlife biologist. Released this year, it was funded for 12 years by Vail Resorts at a cost of approximately $2,000 per year under an agreement with the state Division of Wildlife to monitor development’s impacts on wildlife.

“To the local environments in Pete’s Bowl and the wildlife populations that reside there, disturbance associated with ski-area development and associated human activity cannot be considered benign,” Alldredge concludes.

“I guess I thought we’d see impacts on deer, as well as elk, but didn’t,” said Alldredge. “I thought all that human activity (during construction from 1999 to 2000) would have caused deer to avoid the area as well.

“Deer are so adaptable,” he adds. “They live around humans so much. We can say during that time they were developing, the number of elk appears to decrease when people are in there working. They just avoid the area.”

Since development of Blue Sky Basin was completed, elk and deer appear to have returned to the area, which is closed in summer during elk-calving season.

Small animals

The other study, also funded by Vail Resorts, focused on small mammals. It was conducted by Professor Ken Wilson, also of CSU.

Small mammals, particularly the red-backed vole, a mouse-like rodent, are negatively impacted by the change in habitat from forest to meadow brought by cutting ski trails,” says Wilson.

Voles are a main food source for a number of small predators. Their decline could impact the entire food chain.

“In the area where they did remove all the trees, we see a decline in the red-backed vole,” he says. “You see increases in golden mantle ground squirrels and chipmunks.”

Wilson based his $84,000 study, conducted from 1998-2001, on data from captures and recaptures using live traps in three types of habitat. Those habitat included: a control area that was undisturbed; an area where ski trails had been cut; and an area where ski trails were cut but some logs and forest debris was left as shelter for small mammals.

Wilson and other researchers found ski trails on which shelter was provided helped maintain the numbers of voles in the area.

The debris, however, requires a delay in using the area early in the season because those ski runs need more snow before they can be opened to skiers and snowboarders.

Data from droppings

Some data gathered by researchers literally is a tale of the turd. Researchers surveyed 175 predetermined 60-square-meter plots in the area each year, noting the fecal droppings of animals ranging from porcupines to elk.

The researchers also noted fur, feathers and other evidence of animals. Evidence of 22 animal species was noted, but quantification was made only on deer and elk numbers. Once the evidence is documented, it was removed to prevent carryover from year to year, Alldredge said.

Bad for bunnies

For snowshoe hare, development appears to have had a major impact. When ski trails were cut, they converted habitat from heavily forested hillsides to inclined meadows. The conversion of forest to meadow in Blue Sky Basin, in fact amounted to 21.6 percent of the area.

“We believe it’s reasonable to conclude that development of downhill ski facilities in Pete’s Bowl had a negative impact on snowshoe hare populations,” the study concludes. “Snowshoe hare appear to avoid ski areas. They avoid open areas which may make it easier for predators.”

That’s consistent with what happened to snowshoe hare numbers on the front side of Vail Mountain when it was developed. Few are found there, Alldredge says, adding it could be the result of packed snow on ski trails that opens normally isolated and forested terrain to predators, such as coyotes.

Snowshoe hares, meanwhile, are the preferred prey of the Canada lynx, a shy predator around which development of then Category III hinged. Had the tuft-eared cat is being considered threatened species listing, used to inhabit the area, it would have made developing Blue Sky Basin more difficult, or impossible.

No lynx have been found in decades.

Cute little squirrels?

There may be another, darkly natural reason snowshoe hare appear to be dying out. In a Canadian study of snowshoe hare, Alldredge says, one of the prime predators of young hare was a surprise.

“The No.1 predator there was squirrels,” he says.

The number of hares in the area may be down as much as 30 percent, he adds. It’s possible the compression of habitat caused by cutting ski trails brings the squirrels and hares into closer proximity in the remaining forested habitat.

Meanwhile, other species – porcupine, pine squirrels and red-backed voles – also have declined, the study notes, probably due to changes in habitat, Alldredge says. These species are dependent on unbroken forest, some of which was carved up when ski trails were cut.


While the study is based on the best science available, it’s difficult to pin down facts when dealing with wildlife outside a laboratory. Sheep grazed the survey area for three of the survey years, complicating interpretation of the data, but the herder, at the urging of researchers, moved the flock elsewhere. Sheep pellets and deer pellets are almost indistinguishable.

“Many factors, including uncontrolled environmental variation, changes in wildlife population sizes, unknown levels of human disturbance in the study area and presence of domestic sheep confounded the interpretation of our results,” the study says.

But one thing that did increase substantially during the study period – the amount of trash left behind by humans.

Alldredge says the study will continue for another three years.

Cliff Thompson can be reached at 970-949-0555 x450 or

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