Caribou migrate a long way — but wolves travel even farther

By David Frey

Researchers found that caribou have the longest migration on earth. ©Bob Wick/Bureau of Land Management

In the battle between wolf and caribou, who wins? This isn’t a battle for survival. This is bragging rights for long-distance travel.

Researchers set out to determine which species globally are on the move the most, both in terms of round-trip migration and total annual movement. TWS member Kyle Joly, a wildlife biologist with the National Park Service, led the effort, in part to see if it was true that caribou — a species he studies — really did have the world’s longest migration.

“It really hadn’t been validated very robustly,” Joly told the New York Times.

In a recent study published in Scientific Reports, he and a team of 16 co-authors, including researchers in Germany, Austria, Scotland, Mongolia and China, looked at mammals known for long migrations and gathered datasets on their movements. They concluded that the accepted wisdom appeared to be true.

“We found that caribou likely do exhibit the longest terrestrial migrations on the planet,” they wrote.

Does that mean they travel the farthest? Not so fast.

“Over the course of the year, gray wolves move the most,” they found, likely because wolves travel with their far-ranging prey.

Using round-trip, straight line measurements as their yardsticks, researchers found two caribou herds in Canada — the Bathurst and Porcupine herds — hold the record for the longest migrations, each at 1,350 kilometers.

Gray wolves (Canis lupus) in Alaska may roam four times that distance in a year, though. And a wolf in southwest Mongolia held the record. The male wolf was documented traveling 7,247 kilometers in a year.

Other top migrators included mule deer (Odocoileus hemionus) in Wyoming and Idaho, which logged a 772-kilometer migration; Tibetan antelope (Pantholops hodgsonii), with a 700-kilometer migration and blue wildebeest (Connochaetes taurinus), which migrate 650 kilometers across the Serengeti.

Species with top annual movements included the khulan, or Mongolian wild ass (Equus hemionus), and the Arctic fox (Vulpes lagopus) in northern Canada.

This isn’t just a tally for the record books. The numbers are important, researchers wrote, because these long-distance migrations are “globally imperiled, especially for large mammals, and many have already been extinguished or are under threat. Loss of migration is cited as a threat to declines of large herbivores worldwide and once migratory patterns are lost, they may never resume or take decades for populations to relearn.”

Barriers like fences, roads and habitat loss are disrupting these migration patterns, the authors wrote, and climate change could bring further complications.

Understanding how these animals migrate and move, they concluded, could help guide conservation efforts to protect them.

David Frey is managing editor at The Wildlife Society. Contact him at dfrey@wildlife.org with any questions or comments about his article. Read more of David's articles here.

You can follow him on Twitter at @davidmfrey.


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