Bighorn Sheep and Moose Learn Migration Then Pass Knowledge on to Next Generation

Passing traditions and knowledge from one generation to the next may seem like a uniquely human phenomenon, but a new study published in the journal Science argues that hooved animals, or ungulates, rely on similarly accumulated knowledge to guide their seasonal migration.

According to the Associated Press’ Malcolm Ritter, researchers from the University of Wyoming analyzed the movements of 267 bighorn sheep (females are called ewes, while males are better known as rams) and 189 moose to determine whether their winter migration from mountainous breeding grounds to milder, low-altitude habitats, and vice versa during the spring, is genetically hardwired or passed down from generation to generation.

Researchers report that 129 of the bighorns belonged to herds that have lived in the testing region of Wyoming, Idaho and South Dakota for more than 200 years, Jason G. Goldman writes for National Geographic. Arriving on the scene between 10 and 110 years ago, 59 sheep and 189 moose were considered relative newcomers, and the remaining 80 sheep were recently translocated to the new grazing site in the last decade.

The team compared the ungulates’ migration routes to the quality of vegetation found along their paths, theorizing that members of centuries-old herds would be more adept at tracking down high-quality food.

This hypothesis proved correct, Science magazine’s Elizabeth Pennisi reports. Bighorns from established herds easily located rich vegetation, while bighorns and moose from the group of relatively new herds exhibited mixed results. Animals that had just been translocated largely failed to migrate, instead settling for plants found in their immediate surroundings.

Overall, NPR’s Nell Greenfieldboyce notes that less than 9 percent of the newly relocated bighorns migrated, paling in comparison to the 65 to 100 percent of established bighorns that successfully made the trek. Those that attempted to migrate had previously been integrated into existing herds, Goldman explains, suggesting knowledge can pass from one adult bighorn to another rather than solely across generations.

"If a migration is lost, from some sort of disturbance to the landscape that cuts their migration off, it takes a long time for these migrations to re-establish because they require animals to learn about their landscape, pass that knowledge on to young, who then augment that knowledge with their own experiences and then pass that on to young, and so on and so forth," lead author Brett Jesmer, an ecologist at the University of Wyoming, tells Greenfieldboyce. "It's this really slow development of knowledge over time that allows them to optimally use their landscape and begin migrating."

According to The Atlantic’s Ed Yong, the researchers' findings place the bighorns’ learning curve, or the time needed to “effectively exploit their environment,” between roughly 50 to 60 years. Moose are a bit slower on the uptake, requiring about 100 years to fully understand their habitat.

The new study highlights the necessity of conserving existing migration corridors, NPR’s Greenfieldboyce writes. For animals that rely on learned migration patterns rather than innate genetic instincts, accumulated knowledge and thriving physical landscapes are equally essential to survival.

“The [migration] corridor exists in the minds of these animals,” study co-author Matthew Kauffman, a zoologist at the University of Wyoming, tells Yong. “If you sever it with a highway and then un-sever it with an overpass, the animals wouldn’t necessarily immediately start using it again, because they wouldn’t automatically have the memory of it. They’d need to relearn.”

Meilan Solly | | READ MORE

Meilan Solly is Smithsonian magazine's senior associate digital editor, history.