When times get lean in winter, starving bull elk literally have to choose between eating and being eaten, U.S. researchers reported on Tuesday.
They said male elk were grazing so voraciously in Montana that they were allowing wolves to walk right up and eat them.
The problem seems to be that the elk are so thin that they cannot afford to stop gobbling to look around for danger, the team at Montana State University said.
"The bulls will pretty much keep eating until you pry the grass from their cold, dead lips," said ecologist Scott Creel.
Female elk, in contrast, store more body fat and can afford to look up every once in a while, Creel found.
"For elk in winter, there's a trade-off between doing the things that will keep them well fed and doing the things that minimize the risk of falling prey to wolves," Creel said in a statement.
The researchers originally believed that bull elk were simply unafraid of wolves because of their size.
Writing in the journal Animal Behavior, Creel and colleagues noted that a bull elk can lose more than 100 pounds (40 kg) during the mating season between September and early November.
"They probably can't afford to be as vigilant as cows," said researcher John Winnie, who worked on the study. "They simply cannot stop grazing since they are already in such crummy shape."
Researchers also discovered that elk break up into smaller groups when wolves are around, instead of forming larger herds for defense.
This finding surprised them and may be because it is harder for the wolves to find smaller groups of elk, they said.
