Shearwater
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What is a shearwater?
Shearwaters are seabirds in the family Procellariidae, which also includes fulmars and petrels. The name shearwater comes from their habit of gliding on stiff wings along waves. They are drab, slender-billed birds, ranging from 14 to 26 inches long.
Shearwaters nest in burrows on islands and coastal hills in the North Atlantic, eastern South Atlantic, the Mediterranean, and throughout most of the Pacific. Shearwaters eat small fish and crustaceans close to the surface and will make short dives as necessary.
Some shearwater species have large geographic ranges. For example, the sooty shearwater breeds near Australia, New Zealand, and southern South America and winters in the offshore waters of the Atlantic and Pacific. The Manx shearwater breeds on islands on both sides of the North Atlantic. The slender-billed shearwater spends the year circumnavigating the Pacific.
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Where do shearwaters live?
Shearwaters are seabirds that nest in burrows on offshore islands and coastal hills in the North Atlantic, eastern South Atlantic, the Mediterranean, and throughout most of the Pacific.
Several shearwater species have extremely large geographic ranges. For example, the sooty shearwater breeds near Australia, New Zealand, and southern South America and winters in the offshore waters of the Atlantic and Pacific. The short-tailed shearwaters nest along the coasts of southern Australia and in Tasmania, then migrate across the western Pacific to Japan.
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What do shearwaters eat?
Shearwaters are seabirds that belong to the family Procellariidae. They feed on small fish and crustaceans close to the water's surface, diving briefly as needed. Some larger shearwaters also eat squid.
Shearwaters have been a food source for humans in areas where people have colonized the islands where they breed. For example, the slender-billed shearwater is harvested in large numbers for meat and oil in Tasmania.
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How do shearwaters migrate long distances?
Shearwaters are seabirds known for traveling vast distances during migration. Short-tailed shearwaters, for example, nest in Australia and Tasmania and migrate to the North Pacific and Arctic Ocean. On their return, they travel along the coast of North America and then diagonally back to Australia.
These birds use a combination of methods for navigation, including landmarks, celestial bearings (the sun and stars), and an internal compass sense related to the Earth's magnetic field. Shearwaters take advantage of prevailing winds to help cover long distances. Their capacity to travel swiftly conserves energy.
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What adaptations help shearwaters live at sea?
Shearwaters are long-winged oceanic birds with several adaptations suited for life at sea. They possess slender bills and their ability to glide on stiff wings along the troughs of waves is where they get their common name.
Shearwaters feed on small fish and crustaceans close to the surface, making short dives as necessary. Their life cycle is protracted because they spend most of their lives at sea, and on land, they are clumsy. They nest in burrows and rock crevices, are nocturnal, and are defenseless against predators on land.
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How do shearwaters raise their chicks and keep them safe?
Shearwaters nest in burrows on coastal hills and islands, sometimes in colonies of hundreds of thousands. Both parents incubate a single egg and raise the chick.
After hatching, the downy chick needs warmth from its parents, who feed it an oily broth of digested marine organisms. As the chick grows, parents forage far at sea, returning with food. Before the chick leaves the nest, the parents desert it, and the chick then endures a starvation period before flying.
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Shearwater, any member of more than a dozen species of long-winged oceanic birds belonging to the family Procellariidae (order Procellariiformes), which also includes the fulmars and the petrels. Typical shearwaters are classified in the genus Puffinus, which has approximately 20 species. Shearwaters are drab, slender-billed birds that range from 35 to 65 cm (14 to 26 inches) in length. The common name shearwater describes the birdsâ habit of gliding on stiff wings along the troughs of waves. The name is sometimes also applied to the skimmers, an unrelated oceanic bird family.
Shearwaters nest in burrows on offshore islands and coastal hills in the North Atlantic, eastern South Atlantic, and Mediterranean and throughout most of the Pacific. Colonies may number hundreds of thousands of pairs, and at night, when the calling adults move in and out of the burrows, the din is deafening. A single egg is incubated in turn by the male and female, and the chick is raised by both parents.
Several shearwater species have extremely large geographic ranges. The sooty shearwater (P. griseus) is about 50 cm (19.5 inches) long with a wingspread of approximately 85 cm (33 inches). It breeds near Australia, New Zealand, and southern South America and winters in the offshore waters of the Atlantic and Pacific. The common, or Manx, shearwater (P. puffinus), whose length is 30 to 37 cm (about 12 to 15 inches), is a large species that breeds on several islands on both sides of the North Atlantic. The slender-billed, or short-tailed, shearwater (P. tenuirostris), which is called muttonbird in Australia and whalebird in Alaska, breeds on islands in the Bass Strait of Australia and in Tasmania. It spends the remainder of the year circumnavigating the Pacific. The bird is about 40 cm (16 inches) long, and it is harvested in large numbers for meat and oil.
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Newellâs shearwater (P. newelli) is about 33 cm (13 inches) long and has a geographic range that spans a large portion of the North Pacific Ocean. The IUCN Red List of Threatened Species classified it as endangered despite the presence of several breeding colonies throughout the Hawaiian Islands. The Newellâs shearwater population declined by some three-fifths after Hurricane Iniki passed over the birdâs principal breeding colony on Kauai in 1992. Habitat loss caused by feral pigs and goats further contributed to the speciesâs steady decrease in numbers.
Townshendâs shearwater (P. auricularis) and the Balearic shearwater (P. mauretanicus), both also 33 cm in length, are classified as critically endangered in the IUCN Red List. Townshendâs shearwater faces the greatest threat of extinction of all shearwaters, because it breeds in a single location, Socorro Island, where many individuals are preyed upon by feral cats. A population study performed in 2008 documented fewer than 100 breeding pairs on the island. Although the Balearic shearwaterâs summer range includes much of northwestern and southwestern Europe and the Mediterranean Sea, breeding only occurs on five of the Balearic Islands, where individuals of all ages often fall prey to cats, genets (a catlike carnivore of the family Viverridae), rats, and peregrine falcons (Falco peregrinus). In the water, Balearic shearwaters in search of food are often hooked in fishing lines as they follow commercial fishing boats.