It turns out that South Dakota mountain lions are pretty good at killing vulnerable elk.

Late last month a helicopter crew was tranquilizing elk in Custer State Park, South Dakota to fit the animals with tracking devices, when a cougar stalked in on one of the drugged cows. According to the Rapid City Journal, a mountain lion took killed a sedated elk last year.

Think the lions have caught on to the fact that helicopters mean elk for lunch?

But this time the crew dropped the helicopter low to scare the lion off. This from the Rapid City Journal:

“This year, a lion made a run at an elk Feb. 26. But this time, the helicopter pilot got involved, first buzzing low over the lion, which stopped and stared at the chattering machine but took off after the elk again.

So the pilot got more aggressive and dropped the chopper down to hover between the lion and the elk until the cat gave up and ran into the trees.”

Of the 30 calves tagged in Custer State park last year, 16 were killed by mountain lions. Researchers are monitoring the area to see if a recent lion hunting season will help.