I want to disagree a bit with the wolf vs bear preditation. I don't see bear predation as a significant problem.
Generally, bears will feed on a carcass until the Magpies would have difficulty getting a meal. Bear populations are much slower to grow than are wolves. Bears, again a general comment, have only a couple of offspring of which they stay with a couple of years before the sow will breed again. Meaning a new cub or two every third year. Bears also, another general comment, kill for feed…..often feeding on another's kill or winter kill.
Wolves, on the other hand have been known to act as "thrill killers"…..getting into a group of elk or deer, maiming or killing as many as they can until their lust is fulfilled. Wolves also breed yearly, often having 4 to 6 pups, their numbers can increase almost exponentially. As I understand it, wolves do not feed on a carcass for lengthy period of time before moving on to another fresh kill. Wolves also can do their finest work when deer/elk are on winter range, often in fairly deep snow, congregated together during their weakest most vulnerable period…..whiles bears are sleeping peacefully " with Sugarplums dancing in their heads"!
Just my perspective about wolves vs bears! memtb