A group of about 30 elk warily eyed some potential predators roaming nearby Monday. Some of the animals were standing while others remained on the ground. All had their heads cocked toward the commotion.

It's a scene that sounds like a classic wildlife tale: An elk herd under siege by circling wolves or coyotes in a place like Yellowstone.

But in this case, the "predators" were heavy earth-moving equipment and the location was a ranch in the lower Roaring Fork Valley that's slated for development.

Wildlife officials say it's an all-too-familiar scenario in the valley. As development gobbles the last remaining open spaces in the valley floor, winter range for deer, elk and other wildlife continues to disappear.

Elk used to hang out every winter on the old Sopris Meadows property in El Jebel before it became the Willits development. Aspen Glen was prime winter range for elk long before it became a golf course for humans. Some of the animals adapted and continue grazing on the ranch.

Now the Bair Chase Ranch at Cattle Creek is supplying the latest images of a group of besieged elk. A group that took up residence there when the snow got deep in the high country last fall now appears on edge as heavy equipment buries a ditch on the property.

While the work is scheduled to finish any day now, the former Sanders Ranch property is destined for big changes. There are approvals for an 18-hole golf course, 48 single-family-home lots, 48 multi-family residences and 120 affordable housing units.

Even with a 54-acre conservation easement on the 281-acre ranch, the elk will have to adapt to the changes or go elsewhere for the winter.

Conservationists and the Colorado Division of Wildlife share concerns over shrinking big game habitat across the state.

"We recognize it, a lot of people recognize it, but we're not the land-use decision-makers," said Pat Tucker, area wildlife manager for the region that includes Aspen, Glenwood Springs and Vail.

Tucker wouldn't discuss activity on specific properties but he said loss of winter range is the heart of the issue across the state. The ranch lands in valley floors that have traditionally provided attractive winter range for deer and elk is also prime habitat for homeowners who want a piece of the West.

The issue is critical because the availability and quality of winter range is the key factor in determining the size and health of elk herds. As habitat disappears, it generally causes a loss in the number of big game animals that can be sustained, Tucker said.

The wildlife division isn't sounding an alarm yet in the Roaring Fork Valley. "We are very close to having the number of elk we want in this area," Tucker said.

But the loss of winter range creates uncertainty. Will the elk adapt to wintering around houses in places that used to be meadows, or will they move to different range, which might not support as many animals?

"The other part of it is, where else are they going to go?" Tucker said.

Jonathon Lowsky, a former Pitkin County government wildlife biologist and current owner of Wildlife and Wetlands Solutions consulting business, agreed that development of the area he calls Eljecarbonwood" - representing El Jebel to Carbondale and Glenwood Springs - raises huge concerns for deer and elk.

"As those old ranches get developed, the elk are getting pinched in more," he said.

Elk show they can adapt. It's common to see 60 head of elk bedded down between houses, he noted. But just because they tolerate the situation doesn't mean they like it or that it isn't taking a toll.

"While they are laying there chewing their cud, they are burning more calories then they should be," Lowsky said.

Stressed elk burn more calories and use energy they should be conserving to survive the winter. If they burn more energy dealing with stressful conditions in their winter range, that means they might not have the ability to deal with late-season snow storms, Lowsky said.

Both Lowsky and Tucker said independently that a severe winter will be the real test of the health of the elk population. A decade of relatively mild winters has kept significant patches of winter range open. But if the valley floor is covered in deep snow it's unknown if enough severe winter range on the sun-exposed southerly slopes exists to sustain the deer and elk.

"What's going to happen to animal populations down there?" Lowsky said.

Mike Regan, a resident of Missouri Heights, shares that concern. He said he was outraged to see work begin at Bair Chase Ranch while elk were wintering there.

"It's complete disregard for all those animals - and I'm not a tree hugger," Regan said. "Here they are driving a DC10 over their habitat."

He contended that the disturbance has sent more elk out onto nearby Highway 82. He said he saw "five or six" elk killed in that stretch of road two weeks ago, including two elk calves.

Scott Condon's e-mail address is scondon@aspentimes.com