Tiny Tern Makes World-Record 44,000-Mile Migration
If you thought George Clooney’s character in “Up in the Air” racked up a lot of frequent flyer miles, you should meet his avian rival, which flies the equivalent of three round trips to the moon and back during its lifespan. For a study in the Proceedings of the National Academy of Sciences, researchers tracked the arduous migration of the tiny Arctic tern and found that it flies an average of 44,000 miles every year on its trip from Greenland to Antarctica and back. That’s a new world record.
Scientists suspected that this tern could best the previous world record of 39,000-mile migrations by the sooty shearwater, though they previously lacked tracking devices small enough for the bird to carry. But the team used a tiny tracker developed by the British Antarctic Survey, which weighs just a twentieth of an ounce (1.4 grams)—light enough for an Arctic tern to carry on a band around its leg [National Geographic]. This device reported the birds’ position twice daily.
The locating devices reported back a few surprises. It turns out that the birds did not immediately travel south, but spent almost a month at sea in the middle of the North Atlantic Ocean. The researchers believe the birds use this lengthy stop-over as a chance to “fuel-up” with food before continuing on to less fruitful waters farther south [LiveScience]. In addition, the birds don’t fly a direct path from Greenland to Antarctica and back, but zigzag across the Atlantic Ocean—the map’s yellow lines show the terns jogging between Africa and South America on their northward journey in the spring.
These diversions took advantage of prevailing global wind systems to help the birds preserve energy, according to Carsten Egevang, from the Greenland Institute of Natural Resources [The Independent]. They also roughly double the distance that terns must fly, earning them this new record.
Not all tern migrations are created equal: The shortest in the study measured about 36,000 miles, the longest about 50,000. All in all, it adds up to a well-traveled lifetime. Terns can live on the long side of 30 years, and flying 44,000 miles every year for that length of time can add up to about 1.5 million miles, or about three lunar round trips.
Image: Carsten Egevang