Sooty Shearwater

Fascinating facts about the Sooty Shearwater

• Imagine a bird that circles the globe year after year, covering up to 74,000 km in a single migration, that's the distance a New Zealand-breeding sooty shearwater can travel in twelve months, averaging more than 500 km each day. It departs its breeding islands in March, rides the western side of the Pacific and Atlantic, hits sub-arctic waters in June-July, then heads back south by September. This nonstop odyssey makes it one of the longest-distance travelers of any animal on Earth.
• When a pair of these birds start breeding in October, the female lays a single egg that measures just 48 mm wide and 77.5 mm long. The egg incubates for about 54 days, and once the chick hatches, both parents feed it for 86 to 109 days before it fledges. The whole effort happens in dark, night-only visits to burrows that are lined with plant material to avoid gull and skua predators.
• A single sooty shearwater can dive as deep as 68 m to chase fish and squid, yet it more often skims the surface, hanging out behind whales or fishing boats to snatch up disturbed prey. This flexible foraging lets it thrive across oceans, from the icy waters off north Norway to the warm seas around New Zealand. Its diet overlaps heavily with that of the great shearwater, showing how closely related species can share the same food niche.
• Every year, about 250,000 chicks are harvested by Māori people in New Zealand for oil and food, a cultural practice known as muttonbirding. The harvest targets fledglings just before they leave their burrows, which are then plucked and often preserved in salt. Climate change was already suspected in 2022 of threatening this tradition, linking environmental shifts to the loss of a historic food source.
• In August 1961, thousands of sooty shearwaters crashed onto Monterey Bay’s shore, vomiting anchovies, striking objects, and dying in streets, a mass mortality that helped spark Alfred Hitchcock’s 1963 thriller *The Birds*. Scientists later found that 79% of the plankton in the area contained toxin-producing algae, likely poisoning the birds. The incident underscores how human-altered coastal runoff can trigger cascading effects on marine wildlife.

At a glance

About the Sooty Shearwater

The sooty shearwater (Ardenna grisea) cuts a sleek, dark silhouette against the ocean, its chocolate-brown plumage glinting with a silvery under-wing stripe that only appears in good light. Measuring 40–51 cm in length with a 94–110 cm wingspan, it flies with the stiff, side-to-side “shearing” motion of its genus, its wingtips almost skimming the sea as if a miniature albatross were gliding low over the waves. By night on the breeding islands, small outcrops scattered across southeast Australia, New Zealand, the Auckland and Phillip Islands, the Falklands, Tierra del Fuego and Tristan da Cunha, these birds become vocal, filling the darkness with loud coos and croaks as they tend burrows lined with plant material, emerging only under cover of darkness to avoid gulls and skuas. Their life cycle is a marathon: breeding begins in October, incubation lasts about 54 days, and the chick is fed for 86 to 109 days before fledging, after which the adults embark on one of the longest migrations on Earth. They travel northward along the western edges of the Pacific and Atlantic, reach sub-arctic waters in June–July, cross eastward, and return south in September–October, covering up to 74 000 km in a year and averaging more than 500 km per day. A surprising trait is their willingness to follow whales and fishing vessels, diving to 68 m but often snatching surface prey disturbed by these larger animals, a behavior that links them tightly to the health of marine ecosystems

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