A relocation plan aimed at reducing the elk herd in Wind Cave National Park and building elk numbers nearby has some critics worried about the spread of chronic wasting disease.
Wildlife officials at Wind Cave and adjoining Custer State Park are cooperating on a plan to use helicopters in early March to push hundreds of elk out of Wind Cave, where they have outgrown available habitat. The plan is to reduce the number of elk in Wind Cave and bolster the elk population in the adjoining national forest and Custer State Park, where the elk herd has dropped.
It is considered a win-win plan by those involved, but it worries critics who include former state Game, Fish & Parks Department wildlife specialist John Wrede of Rapid City. And chronic wasting disease is at the heart of that worry.
Wind Cave has been in a troubled area for the fatal brain disorder affecting elk and deer since a CWD-infected captive elk herd on private land adjoining the park had to be destroyed in the 1990s.
CWD apparently spread from that captive herd into wild elk in the park, causing a problem there that, based on limited data, appears to produce higher rates of infection in elk than elsewhere in the Black Hills.
"When considering just elk, the prevalence rate in and immediately around Wind Cave is far greater than anyplace else in South Dakota," Wrede said. "In fact, you could put Wind Cave directly in the center of what could easily be referred to as an endemic area, where managers and epidemiologists should be trying to figure out how to keep the area from growing larger."
Forcing hundreds of elk out of the park seems to work against such containment, Wrede said.
Wind Cave wildlife officials argue that a drive is unlikely to cause a significant increase in CWD elsewhere in the Black Hills. They also point out that the elk herd in Wind Cave is thriving in spite of CWD, to the point where the reduction plan was needed.
And the higher rates of CWD in the park's elk herd should be kept in perspective, said park biological science technician Duane Weber and natural resource manager Greg Schroeder.
They admit that the numbers of infected elk appear startling, based on limited survey results. Out of 140 elk tested in the park since 1998, 45 have tested CWD positive.
But there's a catch. Those were not random tests. They were tests on elk that were either dead or sick, unlike the more random testing done elsewhere in the Black Hills by GF&P, primarily from elk shot by hunters.
Those test results, based on 15 years of sampling, indicate a CWD infection rate throughout the Hills in deer and elk of slightly less than 1 percent. But comparing the two types of tests isn't fair, Weber said.
"The animals we test are either sick and we suspect chronic wasting and we shoot them, or they've already died and we test them," Weber said. "So it's way higher. Comparing our tests to the state's results is apples and elephants."
It's difficult to know what a more random testing system would show, since Wind Cave doesn't allow hunting within park boundaries.
"In a nutshell, we don't have a very good handle on what our prevalence is, whether it's higher or lower overall," Weber said.
The closest study Wind Cave has to the more random state surveys was a 3-year mortality study based on elk fitted with tracking collars. It indicated that 3 percent of the collared elk that died were CWD infected. For perspective, that was the same rate as those determined to have been killed by mountain lions in the park.
Hunter mortality on those collared elk was 6 to 7 percent, on animals that migrated outside the park during the hunting season, Weber said.
Weber and Schroeder said it should also be noted that Wind Cave elk have been moving in and out of the park for years. Portions of the herd have moved over low spots in fences to reach federal or private forest for calving season, Weber said.
Recent upgrades give Wind Cave officials more control over when and where elk leave and return to the park.
Wrede is pretty sure the Wind Cave rates are higher, regardless of variations in testing protocol. The CWD problem in the Black Hills pretty clearly began with the captive elk herd near Wind Cave and spread into the wild elk in the park and then beyond, he said.
"There may be a better than fair probability that, at least in the case of elk, animals historically testing positive for CWD had origins in Wind Cave National Park," Wrede said.
The issue isn't lost on John Kanta, GF&P regional wildlife manager in Rapid City. He noted that elk have migrated in and out of Wind Cave for years but also said the helicopter drive will get into parts of the population that tended not to leave the park. And now they will.
"We're certainly going to be pushing some animals into areas where they haven't been before, from a place where there has been a higher prevalence of the disease," Kanta said."That's certainly a concern that we've discussed among the staff."
Even so, Kanta doubts the CWD impacts outside the park will be dramatic. And he said the upside of redistributing elk will benefit Wind Cave wildlife and habitat management and hunters and wildlife watchers outside the park.
Building the herd in Custer State Park, where limited elk hunting is typically allowed, and on U.S. Forest Service land nearby will benefit elk hunters and elk watchers, Kanta said.
Weber said the positive side of the plan is big.
"We don't know exactly what's going to happen when these elk go out," he said. "But we think the benefit of this project far outweigh any detriments we might see."