Here is Proof, Had they not allowed the wolf packs killed…. They wouldnt need to send 900 Bison to slaughter… Or Kill Elk in Idaho!
But when a pack of wolves is large enough and the conditions are right, the canines will turn their attention to bison.
“Elk are smaller and they aren’t as aggressive as bison,” MacNulty said. “The odds of a successful elk kill are three times higher than with an encounter with bison.”
An earlier study MacNulty worked on noted that wolves in groups of more than four tend to hold back when pursuing elk and let others take the risk of injury during the hunt.
“Given a choice, wolves will stay out of harm’s way until it’s safe to enjoy the spoils of the hunt,” he said.
But when wolf packs hunt Yellowstone bison, the group typically involves nine to 13 canines cooperating in the effort. Even then, a kill is not always the result.
MacNulty says some of the largest Yellowstone wolves are about 140 pounds. Elk run up to 700 pounds and a bull bison can easily weigh more than twice that — up to a ton.
via New research shows Yellowstone wolves pick their prey based on pack size | The Salt Lake Tribune.