Which Mammals on Land Migrate the Farthest?

Whales, eels, birds, and even ladybugs are known for epic migrations that take them hundreds or even thousands of miles through the air and across the sea.

But the land has its fair share of long-distance travelers, too. Recently, an international team of researchers set out to determine which terrestrial mammals migrate the farthest, and just how incredible their journeys are. They published a ranking last month in Scientific Reports.

Caribou, those stately ungulates from North America, have “long been credited with the world’s longest migration,” said Kyle Joly, a wildlife biologist with the National Park Service who studies caribou, and the study’s lead author. But for decades, that claim relied on a single paper. “It really hadn’t been validated very robustly,” Dr. Joly said.

He decided it was time to double check — and to “see if there’s another animal out there that might take the crown,” he said. He and his collaborators started asking around for data sets, and amassed dozens from across the globe. They measured each distance as the crow flies, from where the animals started to where they ended up, and then back again.