| Shearwaters | |
|---|---|
 | |
| Great shearwater | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Procellariiformes |
| Family: | Procellariidae |
| Diversity | |
| Genera | |
Shearwaters are medium-sized long-wingedseabirds in thepetrel familyProcellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and arepelagic outside the breeding season.
Thesetubenose birds fly with stiff wings and use a "shearing" flight technique (flying very close to the water and seemingly cutting or "shearing" the tips of waves) to move across wave fronts with the minimum of active flight. This technique gives the group its English name.[1] Some small species, like theManx shearwater arecruciform in flight, with their long wings held directly out from their bodies.
Many shearwaters are long-distance migrants, perhaps most spectacularlysooty shearwaters, which cover distances in excess of 14,000 km (8,700 mi) from their breeding colonies on theFalkland Islands (52°S 60°W) to as far as 70° north latitude in the North Atlantic Ocean off northern Norway, and aroundNew Zealand to as far as 60° north latitude in the North Pacific Ocean off Alaska. A 2006 study found individual tagged sooty shearwaters from New Zealand migrating 64,000 km (40,000 mi) a year,[2] which gave them the then longest known animal migration ever recorded electronically (though subsequently greatly exceeded by a taggedarctic tern migrating 96,000 km (60,000 mi)[3]).Short-tailed shearwaters perform an even longer "figure of eight" loop migration in the Pacific Ocean fromTasmania to as far north as the Arctic Ocean off northwest Alaska. They are also long-lived: a Manx shearwater breeding onCopeland Island, Northern Ireland, was (as of 2003/2004) the oldest known wild bird in the world;ringed as an adult (when at least 5 years old) in July 1953, it was retrapped in July 2003, at least 55 years old (also now exceeded, by aLaysan albatross). Manx shearwaters migrate over 10,000 km (6,200 mi) to South America in winter, using waters off southern Brazil and Argentina, so this bird had covered a minimum of 1,000,000 km (620,000 mi) on migration alone.
Following the tracks of the migratoryYelkouan shearwater has revealed that this species never flies overland, even if it means flying an extra 1,000 km. For instance, during their seasonal migration towards the Black Sea they would circumvent the entirePeloponnese instead of crossing over the 6 kmIsthmus of Corinth.[4]
Shearwaters come to islands and coastal cliffs only to breed. They are nocturnal at the colonial breeding sites, preferring moonless nights to minimize predation. They nest inburrows and often give eerie contact calls on their night-time visits. They lay a single white egg. The chicks of some species, notably short-tailed and sooty shearwaters, are subject to harvesting from their nest burrows for food, a practice known asmuttonbirding, in Australia and New Zealand.
They feed on fish, squid, and similar oceanic food. Some will follow fishing boats to take scraps, commonly the sooty shearwater; these species also commonly followwhales to feed on fish disturbed by them. Their primary feeding technique is diving, with some species diving to depths of 70 m (230 ft).[2]
There are about 30species: a few larger ones in the generaCalonectris andArdenna and many smaller ones inPuffinus. Recent genomic studies show that Shearwaters form a clade withProcellaria,Bulweria andPseudobulweria.[5] This arrangement contrasts with earlier conceptions based on mitochondrialDNA sequencing.[6][7][8]
The group contains 3 genera with 32 species.[9]
There are two extinct species that have been described from fossils.
Phylogeny of the shearwaters based on a study by Joan Ferrer Obiol and collaborators published in 2022. Only 14 of the 21 recognised species in the genusPuffinus were included.[10]
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||