Killing off the disease-plagued bighorn sheep herd in Custer State Park is not a serious option at this point, state Game, Fish & Parks Department Secretary Jeff Vonk said Wednesday.
And Vonk doubts it will become one while he is in charge.
"It's not even on the table, I mean to kill them all," Vonk said. "It would take a whole lot more research before we'd even consider that as an option. And I'm not convinced that we could bring in a new herd that would be clean and have it stay clean."
Instead, park managers will continue working with university specialists in bighorn sheep diseases in hopes of finding a treatment for the herd, which has dwindled from about 200 animals before the pneumonia outbreak five years ago to a count last fall of 28.
Custer State Park Superintendent Richard Miller confirmed Tuesday that extermination was one of the options for dealing with an ongoing pneumonia problem among bighorns in the park. Miller said the option would not even be considered without another year or more of surveying the dwindling herd.
But Vonk, who is the ultimate supervisor of wildlife and park divisions within the department, followed up on Miller's comments Wednesday by saying that extermination of the park herd is not something he would be likely to support.
"I'm sure people have talked about that. But they've never discussed it with me," Vonk said. "I don't want to be quoted as saying we would never do that. But it's not even a feasible option in the near future."
Pneumonia has been a problem for bighorns in other states, including Montana and Idaho. There are about 350 bighorn sheep in the Black Hills outside of Custer State Park. But only the park's small bighorn herd has suffered severe losses from the pneumonia.
Custer State Park sheep can wander outside park boundaries. Department biologists suspect the initial infection of the Custer Park herd could have come from contact with domestic sheep outside the park.
"I think we believe that, because our policy today is that in the event we find a ram out intermingling, we try to kill it, because we don't want to get further infections," Vonk said.
There is no indication that the pneumonia has spread to other bighorn herds in the Black Hills, including those near Hill City, Spring Creek south of Rapid City and immediately west of the city.
Because the Custer State Park herd is small and easily accessible, antibiotic treatment is possible, Vonk said. So far, however, such treatment has not been successful, he said.
"We've shot antibiotics into a couple of them and really haven't seen the kind of effects we'd like," he said. "The ewes still get pregnant. They still drop lambs. The problem is we've essentially got zero survival of lambs in that herd."
Vonk said there's an inclination by some people to presume mountain lions are killing the lambs. There's no evidence that the main problem in the park's bighorn herd is lions, he said.
"I'm not here to tell you there isn't any lion predation on those sheep," he said. "But we believe this is pretty much disease related."
Park staffers have located sick lambs before they died, and know that it was illness and not predators that killed them, he said. Tests have also confirmed the presence of the disease as well, he said.
Typically the department works with South Dakota State University on wildlife disease and research issues. But Washington State University specializes in bighorn research, and Custer State Park is cooperating with the school as part of a project on bighorns across western states, Vonk said.
"This die-off thing is not just here," he said. "It's really across much of the bighorn range."
Contact Kevin Woster at 394-8413 or firstname.lastname@example.org