Jackson Elk Herd May Be Forgetting Migration Route To Yellowstone

Dec 20, 2017

Credit US Fish and Wildlife Service
The graph shows a dramatic decrease in the percentage of collared elk that migrate to Yellowstone (shown in purple on the pie chart series) and the dramatic increase in the Short-Distance Migrants (shown in red on the pie chart series). All elk captured for this research were randomly collared on Refuge feed grounds during the winter.

Very few of the elk that winter every year on the National Elk Refuge outside Jackson are making their traditional long migration all the way to Yellowstone National Park for generations, and wildlife biologists are worried they’ll eventually forget the route altogether.

Back in the 1970’s, almost 30 percent of the Jackson elk herd migrated the 50 miles to Yellowstone. Now only two percent make the trek. Elk Refuge biologist, Eric Cole, said the reason for the steep decline is that fewer elk calves are surviving to remember the longer routes than calves that make other shorter migrations of ten miles or so.

Cole said elk calves aren’t born knowing migration routes. They have to learn them from their mothers.

“It’s not individual elk deciding their going to change where they migrate to,” he said. “What’s happening is the percentage of calves that survive to adulthood is much lower for these Yellowstone migrants compared to the short distance migrants.”

Cole said the shorter migrations from Wilson to Moose have more calves surviving to learn those routes. He said there are a couple possible reasons for that.

“It is true that there is higher predator density in southern Yellowstone than we see in the areas where the short distance migrants summer,” said Cole. “Another alternative explanation is forage quality could potentially be better. We don’t know. We have to explore that further.”

Cole said if the Jackson elk herd does eventually forget the route, the loss will be part of a global decline since long-distance migrations are imperiled worldwide.