RENO, Nev. (AP) — Nevada wildlife officials are waiting anxiously to see if their decision to slaughter a diseased herd of bighorn sheep earlier this year paid off in saving a neighboring herd near the Idaho line.

It's part of an effort to combat the spread of bighorn pneumonia that's hit several western states and threatens future efforts to rebuild the native populations that were on the brink of extinction a half century ago.

Nevada officials decided in February their only choice was to kill the last 27 survivors of a sickly herd that once totaled about 100 near the Oregon line.

Ed Partee, a game biologist who's spent much of his 24-year career rebuilding bighorn populations, drew the grim task of tracking and gathering the carcasses.

He says it's one of the hardest things he's done.