The sooty shearwater undertakes a roughly 64,000-kilometre annual migration between the Southern Ocean and the North Pacific.
It breeds mainly on islands around New Zealand, Australia, and southern South America. After breeding, many birds travel north through the Pacific, where they feed in productive waters off Japan, Alaska, and western North America. They later return south for the breeding season.
The distance is an annual circuit, not a single nonstop flight. Sooty shearwaters use prevailing winds and ocean productivity, and their route can form a giant loop. Large concentrations have been recorded off California during northward migration.
They are sometimes confused with smaller shearwaters, but adults are dark brown overall, with silvery underwings. Their migration is among the longest known for any animal.