The Migratory Patterns of Arctic Terns

The Arctic tern undertakes the longest migration known in the animal kingdom, travelling from its Arctic breeding grounds to the Antarctic and back again each year. Over a lifetime this amounts to a distance roughly equivalent to three round trips to the Moon, a feat of endurance that has fascinated ornithologists for well over a century of careful study.

Researchers tracking individual birds with geolocators have found that the terns do not follow a straight path. Instead they trace a sweeping S shaped route down the Atlantic, exploiting prevailing wind systems to conserve energy across the open ocean where food is scarce and the weather is famously unforgiving to anything that tires before landfall.

Conservation of the species depends on protecting both polar habitats and the staging areas in between, where the birds pause to feed during their extraordinary annual journey between the two ends of the Earth.