These tiny birds make the most extreme migration ever

This is the northern wheatear, a tiny insect-eating Arctic bird. Every year, half of the species travels 4,500 miles over Greenland, across the Atlantic, and down through Europe to reach western Africa. And the other half's journey is even more insane.

This little songbird, which is found throughout Alaska and the Canadian Arctic, weighs just under an ounce. That already makes it one of the tiniest birds to migrate, but the sheer scale of its yearly travels is staggering, as a team of German biologists recently discovered. The researchers tagged over thirty birds from both the western and eastern populations with geolocators, then returned a year later to see just where the birds had spent the frigid Arctic winter.

They didn't have a lot of information to work from – only two western birds returned with their tags intact, and only a single tagged eastern bird made it back, but it was enough. The wheaters from eastern Canada left their homes on Baffin Island and flew the 2,000 miles to the British Isles in just four days, most likely traveling over Greenland to get there. They then head south through Europe and flew another 2,500 miles to reach the west African country of Mauritania. It took them just 26 days to make the trip down, and a relatively leisurely 55 days to get back to Baffin Island.

That's the eastern population, which is already making a migration that's orders of magnitude more intense than most species are capable of. But the Alaskan population makes the Canadian birds look like a bunch of wimps. They travel a whopping 9,000 miles each way every year, traveling through eastern Russia and Kazakhstan before crossing the Arabian desert to reach countries in east Africa, most likely Sudan, Kenya, or Uganda based on the geolocator information.

To put this migration into awesome, if admittedly rather ridiculous, perspective, we weigh about 3,000 times as much as these tiny songbirds. Proportionally speaking, we would have to travel roughly 50 million miles to cover the same sort of distance these wheatears do. In other words, for us to migrate on the same scale as these tiny Arctic birds, our entire species would need to travel to Mars and back every single year. (And yes, I'm aware that's not exactly a fair analogy - it's simply too awesome not to point out.)

As the researchers explain in their paper in Biology Letters, the wheatear's migration patterns likely date all the way back to the Pleistocene, which means these birds might well have been making their transcontinental trips long before humans even reached the Americas. In all those thousands of years, the birds have apparently never decided to just stay in the Arctic for the winter, or even settle on a shorter journey to the warmer parts of the Americas. That means that there must be some serious evolutionary incentive for these birds to keep on making this journey, or at least no good reason for them to abandon it. The most likely explanation? The birds just enjoy being complete, globetrotting badasses way too much to stop their mega migrations.

Check out the full paper at Biology Letters. Image by Seabamirum on Flickr.