ROCKY MOUNTAIN NATIONAL PARK — Government scientists are grappling with unchecked elk herds infected with a mysterious disease.

So as a third round of culling begins to try to reduce the size of the herd, National Park Service chief veterinarian Margaret Wild is taking the lead.

The dart gun she fires from a federal truck finds an easy target — a female foraging in a snow-dusted meadow in the park west of Estes Park, which hosts the densest elk population in the Rocky Mountain region.

The 550-pound elk staggers and bolts for forest until, after three minutes, it wobbles and keels sideways. Wild races to the animal with a team of researchers. They conduct a swift surgery — extracting saliva, blood, urine, feces, tissue samples. Wild then injects the animal with a lethal serum.

The elk is one of 50 that researchers and volunteer sharpshooters will kill over the next few weeks as they thin the park’s burgeoning herd. The culling quota is increasing, up from 40 elk last winter and 33 two years ago.

Wildlife managers estimate about 2,350 elk range through Rocky Mountain National Park east toward Loveland. These include a resident herd of about 1,700 in Estes Park.

Hunting prohibited in park

Elk here multiply rapidly because hunting — encouraged elsewhere to hold herds in check — is prohibited in the park. Few natural predators exist.

But today a new killer — chronic wasting disease — is complicating wildlife managers’ calculus. Federal studies find that one in nine elk in the park are infected.

The samples Wild collects, and brain tissue to be taken later in a Fort Collins lab, are meant to help understand CWD and the extent to which it may reduce herds when predators and hunters do not.

“It’s not natural. This disease really shouldn’t be here killing the elk, and we can’t control it,” Wild said.

“There’s also the risk of it, potentially, spilling over into another species. We just don’t like to have pathogens out there that we can’t manage or control — doing what could be our work to manage the elk to a population that we consider suitable.”

The spread of CWD adds to an already delicate challenge of controlling wildlife in ecosystems hurled out of whack. More and more people are moving into Colorado mountain elk habitat, many of them opposed to hunting. Wildlife advocacy groups are pressing for the re-introduction of predators, such as wolves.

Such is the conundrum that wildlife managers now are experimenting with elk contraceptives as another tool to increase their control.

Ever since settlers arrived, elk and people have clashed. Hunters initially wiped them out. Around 1913, Coloradans reintroduced elk, hauling about 40 by train and truck from Wyoming to this area.

Now nearly 280,000 elk forage around Colorado. State wildlife managers set target numbers of elk that they think can co-exist with people — and allocate hunting licenses accordingly. Roughly 229,000 hunters a year harvest around 47,000 elk — more than entire elk populations in other Western states.

Elk hunting brings Colorado nearly $40 million a year from license fees, sustaining the wildlife agency.

CWD appears less prevalent in herds outside the park, Colorado Division of Wildlife spokesman Theo Stein said. Yet as urbanized mountain communities expand on elk habitat, state managers increasingly field elk-related complaints.

“We’re constantly dealing with changing circumstances and shifting perspectives of society,” Stein said. “It’s never going to be clean. This situation is occurring because we have an abundance of elk.”

Complaints about killings

In the Denver mountain suburb of Evergreen, residents recently called the sheriff when a neighbor shot and killed an elk. And when Hiwan golf course operators deployed a bow-hunter to remove a green- stomping bull, a neighbor who witnessed the killing complained.

“Some people aren’t happy. They didn’t expect to move into an area hoping to enjoy viewing wildlife and watch their neighbors killing them,” said Jefferson County sheriff’s Sgt. Dave Baldwin, who supervised responses to those incidents and others and recently had a close encounter of his own when a bull elk charged his vehicle.

“As long as hunters are within the law, have proper licenses and are hunting in a safe manner, they are certainly within their rights to do so,” Baldwin said. “It’s hard explaining to someone who is not a hunter that hunting is a good thing.”

Denver Mountain Parks naturalist Kelly Uhing said she’s concerned about “overgrazing” as elk move across city property.

“I wish we could bring back wolves,” Uhing said. “I’d love to see that natural balance.”

The culling in Rocky Mountain National Park may be driving more elk into the neighboring town of Estes Park, Mayor Bill Pinkham said.

Elk-related emergencies

There’s now about one elk for every four residents of Estes Park, where a firearms ordinance creates an ultra-safe haven. A relatively tame herd forages across lawns, gardens and a golf course. Tourists delight at calves in the spring and at bull elks jousting in the fall.

But police are busy responding to hundreds of elk-related emergencies. They carry pepper spray, firecrackers and shotguns. Sgt. Jim Kenney said, “We try to tell people, ‘We are not going to be able to keep the elk out of your yard.’ “

Federal researchers remain focused on CWD, which is related to the mad cow disease that worries producers and consumers of beef.

Natural predators are ideal for ensuring herd health, but that requires an acceptance of mountain lions and wolves, Wild said. “Sometimes we don’t get what’s best.”

A proposed reintroduction of wolves was scuttled three years ago because of fear in surrounding communities. Park officials say if wolves arrive on their own, however, rangers will let them stay.

For now it’s a matter of controlling herd size.

“Certainly, the high density of animals is something we are concerned about,” Wild said.

Letting elk multiply and live so close together in a safe zone “increases the likelihood of transmission” of CWD, she said. It spreads through nose-to-nose contact and foraging over areas where infected carcasses have decayed.

“Will diseases start managing these populations?” Wild wonders. “We’d like to be able to manage our wildlife in a way that’s a bit more controlled than a disease, where we don’t know what the disease will do to the population.

“It makes a lot more sense to be able to have management actions than to have disease.”

Bruce Finley: 303-954-1700 or bfinley@denverpost.com