A Slippery Slope
Hikers observe massive Mule Deer casualties at Bishop, Shepherd’s Passes
Several large scale deer mortality incidents were discovered by hikers on Bishop and Shepherd’s passes in the Inyo National Forest in the last two weeks, said Mike Morrison, Wildlife Biologist for the California Department of Fish and Wildlife.
Prior to the most recent storm to hit the Sierra, said Morrison, “the deer were following their migration trail and because of the heavy snow we got last year, there were big fields of it left unmelted. When it got cold it turned to ice and the deer just slipped to their death,” said Morrison this week. He said that 78 deer had been counted dead on Bishop Pass, and 44 at Shepherd’s pass as of Monday, November 20. However, he said, “it’s very possible that there’s a lot more mortality than we know about,” because CDFW relied on hikers who reported finding the deer carcasses.
Lindsey Jackson told The Sheet that she happened upon a boulder field of dead deer below Bishop Pass on November 11. “When I first walked up on it, I was horrified,” she said. At first, she said, she didn’t understand what had caused such a mass die off of apparently healthy deer.
She said when she eventually ascended Bishop Pass she saw the reason for the carnage—a huge ice field above a chute. “I had to use my microspikes if I wanted to keep going,” Jackson said. Jackson said that scavengers had already been at work, with crows circling overhead. “There were enough [dead deer] to mask the rocks,” she said.
Morrison said that the phenomenon is not common, but it has been documented before. A paper titled “Accidental mass mortality of migrating mule deer” published in 2001 by West North American Naturalist and written by Vernon C. Bleich and Becky M. Pierce, cites events in that year, and in 1995 and 1954. “Snow, which is transformed to ice by frequent thawing and freezing, occasionally lasts through autumn at high elevations, and such would be expected following winters of heavy snowfall,” stated the paper.
The paper also reported that public concern at the time led the authors to propose using hand tools to enhance the trail and cover it with sand, but permission at that time was denied by the Inyo National Forest “because it would conflict with ‘natural processes’ in wilderness.”
Morrison said that migrating mule deer “are like lemmings. They could go around it, but their mama brought them that way and that’s the way they’re going. They step on the ice not recognizing it’s going to be slippery. When they get to the point where gravity takes over, it’s too late.”
Morrison also said that it was too early to tell whether the mass mortality event would affect the amount of hunting tags issued next deer season. “We’ll have to sit down and talk about that when the time comes,” he said. “We don’t want to issue a whole bunch of tags knowing there’s going to be a low success rate for those fortunate enough to draw a tag.” He said that it’s the does (female deer) that drive populations, and that the mass mortality events this fall resulted in the deaths of “fawns, bucks, does, everything.”