ROCKY MOUNTAIN NATIONAL PARK, Colo.—A cow elk lay on her side in a meadow ringed by towering, snowy peaks on Friday, rocking back and forth before struggling to her feet.
She had just been darted with an anesthetic, injected with an experimental contraceptive and given a test for chronic wasting disease. A second drug to reverse the anesthesia was taking hold, and after a brief wobble, she bounded off to join the rest of the herd.
This 15-year old is one of 120 female elk in Rocky Mountain National Park undergoing similar treatment from researchers who are seeking reliable, multiyear contraception for wildlife and an easier way to detect chronic wasting, a fatal disease that attacks the brain.
All will get the chronic wasting test, but half will get a saline solution instead of the contraceptive and will serve as a control group.
It will be the first such research conducted on a free-ranging elk herd.
The researchers, from the National Park Service and Colorado State University in Fort Collins, are dovetailing their work with the park’s efforts to reduce its oversized elk herd, which now has up to 3,000 head and is damaging the habitat by overgrazing.
“It gives us a really great opportunity to learn about two major objectives,” said Margaret Wild, a Park Service veterinarian and researcher based in Fort Collins.
Multiyear contraception has been tested on captive animals and on deer in the wild, but not on elk in the wild. Eventually, the birth control could be used in areas where there are too many deer or other wildlife but hunting isn’t an option.
“Fertility control isn’t going to replace hunting,” said Jenny Powers, a Park Service wildlife veterinarian and one of the prime researchers.
But the contraception could be one more tool for wildlife managers, she said.
Hunting isn’t allowed in Rocky Mountain National Park, 70 miles northwest of Denver. Last month, park officials approved a plan to thin the elk herd, which fluctuates between 1,700 and 3,000. The goal is a herd of about 1,600 to 2,100.
The plan calls for specially trained sharpshooters to kill up to 200 elk a year over 20 years, working at night with silencers to keep the culling out of public view as much as possible. The number killed each year will depend on the size of the herd.
Although the elk herd is one of the main tourist attractions in the park, it has nearly eliminated aspens, willows and other native plants in some areas, reducing habitat for other species.
Park biologists have said the area’s elk densities—up to 285 per square mile in some prime winter range—are the highest recorded for a free-ranging herd in the Rockies.
The elk in the test group of 120 will be fitted with radio collars. All will eventually be killed as part of the herd thinning. Wild said that will give researchers a chance to study the carcasses for any side effects from the contraception.
The elk treated Friday was pregnant, which will give the researchers a chance to see what effect the contraceptive might have on animals that have already conceived.
Park officials know that some of the elk in the park have chronic wasting disease. The elk in this test group will be the first to be tested for the disease in the wild.
Tests for the disease can be done easily on dead animals, but detecting it in live animals is more difficult and expensive.
An effective test for live animals could allow managers to cull the diseased animals and spare uninfected ones, Wild said.
The ailment is similar to mad cow disease and was first detected in deer and elk in northeast Colorado and southeast Wyoming. The disease has since spread to other parts of Colorado and other states.
Wild, Powers and Colorado State scientist Dan Baker have radio-collared and tested 83 elk so far. They’re collecting saliva samples for other scientists trying to develop saliva and blood tests for chronic wasting.
