Green Guide

Elk herd to be reduced, studied for chronic wasting disease

Posted 2:01 a.m. Sunday

— Gun-propelled nets streaked down from helicopters and engulfed wild elk last week in Wind Cave National Park as researchers began trapping animals in order to perform a long-term study of a fatal disease.

The researchers are capitalizing on an opportunity to monitor the effects of a large and swift reduction in the park's overabundant elk herd. During the next few months, volunteers assisted by park staff will shoot and kill up to 300 elk, bringing the population down from 550 to around 250, with some of the meat going to a statewide hunger-relief group, the Rapid City Journal (http://bit.ly/2fYJzBl ) reported.

Among the surviving elk will be 40 cows that were fitted with neck collars during last week's helicopter operation. The collars will transmit the location of the elk to researchers for several years, and when a period of inactivity indicates an elk has died, the carcass will be evaluated for causes of death including chronic wasting disease.

Researchers hope to learn whether the lower concentration of elk in the park will slow the spread of the disease, which struck the Wind Cave herd in 2002 and now afflicts an estimated 9.5 percent of the elk. The disease causes brain degeneration, emaciation, abnormal behavior, loss of bodily functions and death.

Glen Sargeant, a research wildlife biologist for the U.S. Geological Survey, said the 53-square-mile park — about 50 miles from Rapid City in the southern Black Hills — will be an excellent laboratory.

"We haven't really understood the role that high population density plays in CWD transmission," said Sargeant, who is based in Jamestown, N.D. "What we're going to learn here is transferable to other places."

The other places include Custer State Park, which shares a border and a colorful history of elk management with Wind Cave National Park.

Elk are native to South Dakota but were hunted and pushed out during the settlement boom of the late 1800s. Elk from other Western states were brought to Custer State Park and Wind Cave National Park in the early 1900s.

The elk thrived in both parks, and public hunting was used to help control numbers in the state park. The federal legislation that created Wind Cave National Park does not allow open public hunting, so park officials sold surplus elk until 1940, used shooters to conduct targeted thinning operations in the 1950s, and began transferring live elk to other tribal, federal and state agencies in the 1970s. The transfers continued until 1997, when the first case of CWD in a South Dakota elk was discovered in a captive herd on private land.

The termination of the transfer program left Wind Cave National Park with few options to control elk numbers, and the elk population grew to 800 by 2004. Around that same time, about 1,000 elk were roaming Custer State Park. Both numbers were higher than each park could sustain.

Then, elk numbers in Custer State Park began declining because of a combination of factors including hunting, predation by mountain lions and a migration outward of elk through vulnerable or open spots in park boundaries. The migrating elk might have been fleeing human visitors, who number nearly 2 million annually at Custer State Park compared with about 600,000 annually at Wind Cave, or they might have been fleeing increased logging activity resulting from a pine-beetle infestation.

"We don't know for sure exactly what caused it, but we do know the population of elk in Custer State Park fell dramatically in a very short time," said Mike Kintigh, Rapid City-based regional supervisor in the Wildlife Division of the state Department of Game, Fish & Parks.

The solution for high elk numbers at Wind Cave National Park and low elk numbers at Custer State Park seemed simple: Just push some elk from the national park over the shared boundary into the state park.

That was tried with the aid of horses and helicopters, but with little success. Some of the elk that were herded into Custer State Park exploited weak spots in the boundary fence to escape back into the national park, and many of the elk that did not escape back into the national park took up residence along the fence line, perpetually looking for a way to get through it.

"The elk were homebodies," Kintigh said. "They did not want to leave Wind Cave."

Meanwhile, an effort to allow a natural migration of Wind Cave elk out of the park through adjustable gates also met with little success.

With the relocation efforts failing and with research revealing a higher prevalence of CWD in the Wind Cave herd than park managers previously suspected, Custer State Park officials declined further elk from the national park, opting instead to grow their own herd in part by limiting hunting licenses.

Wind Cave officials needed another means of thinning their herd, and they settled on volunteer shooters. A lottery was conducted to select 48 volunteers from roughly 1,800 applicants.

From now through February, park staff will accompany the volunteers into the field. The volunteers will first be required to demonstrate their shooting proficiency and physical fitness; if they pass those tests, they will head out on hikes of many miles in pursuit of elk while shouldering packs weighing up to 70 pounds.

Harvested elk will be tested for CWD, and carcasses that are free of the disease will be processed. The volunteer shooters will be eligible to keep some of the meat, and the rest will be given to the nonprofit organization Feeding South Dakota.

Sargeant hopes that sacrificing some elk in the short run will yield findings about CWD to save more elk in the long run.

"Wind Cave is really unique in the sense that we're about to have an opportunity to observe a fairly abrupt change in elk density, and observe population response to that," Sargeant said. "That's kind of a big deal."

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