A disease that nearly wiped out the bighorn sheep population at Custer State Park in South Dakota might be starting to wane. Four of eight lambs born last spring have survived, and biologist Chad Lehman tells the Black Hills Pioneer that officials are optimistic the lambs will make it through the winter. In late 2004, there were about 200 bighorn sheep in the park. A contagious pneumonia then hit, and only about two dozen sheep remain. Lehman says the disease can take as long as 15 years to run its course. The adult bighorns in the park are showing signs of immunity, but lambs are still vulnerable.