Arctic terns fly the longest annual migration of any animal on Earth
Every year, the Arctic tern undertakes an epic journey from its breeding grounds in the Arctic to the ice edges of Antarctica and back. Tracking devices reveal they fly up to 90,000 kilometers annually along winding migratory routes across global oceans. Over a typical thirty-year lifespan, an individual tern can travel over 2.4 million kilometers—equivalent to flying to the Moon and back more than three times.
Two Summers a Year in Perpetual Daylight
The Arctic tern experiences more daylight than any other living creature on Earth. By breeding during the northern hemisphere summer in the Arctic and sub-Arctic tundra and spending the southern summer foraging along the pack ice of Antarctica, the bird effectively moves between two polar summers each year. This extreme annual rhythm ensures that for the vast majority of its life, the tern lives in nearly perpetual day, following peak seasonal bursts of ocean productivity from one end of the globe to the other.
The scale of this migration makes the Arctic tern a true global nomad. Its breeding range covers a circumpolar band across northern North America, Greenland, northern Europe, and Siberia. Once the brief Arctic nesting season ends and chicks fledge, colonies disperse southward over vast ocean expanses. Rather than seeking mild temperate waters, they press onward through the tropics and continue until they reach the edge of the Antarctic ice shelves, where nutrient-rich polar upwellings support massive swarms of marine life.
Unlocking the Route with Miniaturized Geolocators
For decades, biologists understood the general start and end points of the Arctic tern's journey through bird-banding records and coastal observations, but the exact paths across open oceans remained an enduring mystery. Because an adult Arctic tern weighs only about 100 grams, conventional satellite transmitters were long too heavy to attach to the birds without interfering with their flight mechanics, energetics, or survival.