An Arctic tern flies nearly twice around the Earth in a year

Geolocators on Arctic terns recorded annual trips of about seventy thousand kilometres, and more than eighty thousand for some birds. The circumference of the Earth is forty thousand.

Banding had already suggested that Arctic terns breed in the far north and winter in the Antarctic, which is the longest commute anyone could draw. In 2010 Carsten Egevang and colleagues put 1.4-gram loggers on birds from Greenland and Iceland and got eleven tracks back. The birds left the colony, paused in the North Atlantic, then took either the African or the South American side of the ocean south, and came home by a different route. The round trip averaged on the order of seventy thousand kilometres. Some individuals exceeded eighty thousand. That is about twice around the equator, flown not as a stunt but as the ordinary year.

They do not do it in one unleavened push. There are stopovers, and the route bows with the wind. The nonstop champion of this library is a godwit. The tern’s claim is the annual total, repeated, on a body that can sit in a hand. A thirty-year life at that rate is more than two million kilometres. The thirty years is a lifespan from other studies, not from the loggers. The year they logged is enough.