Which bird migrates the longest distance annually?

The Arctic tern migrates the longest distance annually. Each year, it travels between breeding grounds in the Arctic and sub-Arctic and feeding areas near Antarctica, experiencing two summers along the way.

The route is not a straight line. Arctic terns follow winding oceanic paths that take advantage of prevailing winds, so modern tracking has revealed much greater distances than older estimates suggested. Birds breeding in Iceland and Greenland have averaged about 70,900 kilometers on their annual round trip.

One tracked tern from the Farne Islands in England covered approximately 96,000 kilometers in ten months, a distance more than twice around Earth. The species’ migration is widely regarded as the longest known regular migration by an animal.

The Arctic tern’s journey also explains its unusual relationship with daylight. By moving between the northern and southern summers, it sees more sunlight annually than almost any other animal. Its scientific name is Sterna paradisaea, and although small—roughly 100 grams—it can complete this extraordinary global journey repeatedly during its life.