Cory's Shearwater
Encyclopedia
The Cory's Shearwater is a large shearwater
Shearwater
Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...

 in the seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

 family Procellariidae
Procellariidae
The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes , which also includes the albatrosses, the storm-petrels, and the diving petrels.The procellariids are...

.

This species breeds on islands and cliffs in the Mediterranean, with the odd outpost on the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 coast of Iberia
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...

. The nest is on open ground or among rocks or less often in a burrow where one white egg is laid, and is visited at night to minimise predation from large gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

s. In late summer and autumn, most bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 into the Atlantic as far north as the south-western coasts of Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 and Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. They return to the Mediterranean in February. The biggest colony is located in Savage Islands
Savage Islands
The Savage Islands, also referred to as the Salvage Islands or the Selvagens Islands, of Sé. They are designated a Nature Reserve, comprising two areas: one on Selvagem Grande Island and the second on Selvagem Pequena Island.-Geography:...

, Madeira
Madeira
Madeira is a Portuguese archipelago that lies between and , just under 400 km north of Tenerife, Canary Islands, in the north Atlantic Ocean and an outermost region of the European Union...

.

This bird flies with long glides, and always with wings bowed and angled slightly back, unlike the stiff, straight-winged flight of the similarly-sized Great Shearwater
Great Shearwater
The Great Shearwater is a large shearwater in the seabird family Procellariidae. Its relationships are unclear. It belongs in the group of large species that could be separated as genus Ardenna ; within these, it might be allied with the other black-billed, blunt-tailed species Short-tailed...

.

This shearwater is identifiable by its size, at 45-56 cm in length and with a 112-126 cm wingspan. It has brownish-grey upperparts, white underparts and yellowish bill. It lacks the brown belly patch, dark shoulder markings and black cap of Great Shearwater.

There are two subspecies, the Mediterranean subspecies C. d. diomedea, and the Atlantic subspecies C. d. borealis. They are closely similar in appearance, although the Atlantic race is larger, and with a stouter bill. They are best distinguished by the pattern of the underwing. Being fairly distinct (Heidrich et al. 1998), they are sometimes regarded as separate species, C. d. diomedea then being named Scopoli's Shearwater.

Cory's Shearwater feeds on fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, molluscs and offal, and can dive deep (50 feet/15 meters or more) in search of prey. It readily follows fishing boats, where it indulges in noisy squabbles. This is a gregarious species, which can be seen in large numbers from ships or appropriate headlands. The Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...

 ferries are particularly good for this species. It is silent at sea, but at night the breeding colonies are alive with raucous cackling calls.

This bird was named after the American ornithologist Charles B. Cory
Charles B. Cory
Charles Barney Cory was an American ornithologist and golfer.-Biography:Cory was born in Boston. His father had made a fortune from a large import business, ensuring that his son never had to work. At the age of sixteen Cory developed an interest in ornithology and began a skin collection...

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The Cape Verde Shearwater
Cape Verde Shearwater
The Cape Verde Shearwater , or Cagarra locally, is a medium-large shearwater, a seabird in the petrel family Procellariidae. It is a breeding endemic of the Cape Verde archipelago of Macaronesia in the Atlantic Ocean, off the coast of West Africa.-Taxonomy:The Cape Verde Shearwater was originally...

 C. edwardsii (Oustalet
Émile Oustalet
Jean-Frédéric Émile Oustalet was a French zoologist.Oustalet was born at Montbéliard, in the department of Doubs. He studied at the Ecole des Hautes-Etudes and his first scientific work was on the respiratory organs of dragonfly larvae...

, 1883) was once considered a subspecies of Cory's Shearwater but has recently been split off as a separate species (Snow & Perrins 1998). It is endemic
Endemism in birds
An endemic bird area is a region of the world that contains two or more restricted-range species, while a "secondary area" contains one or more restricted-range species. Both terms were devised by Birdlife International....

 to the Cape Verde Islands. It has an all dark, slim bill, and darker head and upperparts than Cory's. The flight has been described as rather more typically shearwater-like than Cory's, with stiffer and more rapid wing beats.

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