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Bird name:

Cory's Shearwater

Calonectris borealis




Petrels and Shearwaters (Procellariidae)





Euring 5

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Breeding Location:

Islands, Islands, rocky

Breeding Type:

Monogamous, Colonial, Mates for life

Egg Colour:

Dull white

Number of Eggs:


Incubation Days:

52 - 58

Egg Incubator:

Both sexes

Nest Material:

Scrape, sometimes lined with plant material; sometimes no lining.

Nest Location:

In burrows, on rocky ground, or in caves.




Cory's Shearwater: Herring Gull sized, long-winged seabird with light brown upperparts, dark brown wings and tail, white underparts, and a pale yellow bill. Also has an indistinct eye ring, pale edging to the feathers of the back, rump and wings, white wing linings, and dark brown flight feathers. Also has small white area on uppertail coverts. Glides near the surface of the water on long, bowed, wings. Flaps wings in a slow, lazy looking manner and occasionally sits on the water. Sexes similar.

Range and Habitat

Cory's Shearwater: Passage visitor to the UK & Ireland. Non-breeding birds summer in coastal areas near southwestern England and Ireland. Birds winter across most of the Atlantic Ocean, also in the southeastern Indian Ocean. Can be seen along beaches and over water while fishing.

Breeding and Nesting

Cory's Shearwater: Nests are often within a metre of one another in breeding colonies. Nests may be in burrows, on rocky ground, or in caves along rocky sea cliffs. Only one egg is laid per breeding pair, and the incubation period may be as long as 62 days. Chick rearing lasts about 100 days.

Foraging and Feeding

Cory's Shearwater: Feeds primarily on fish, squid, mollusks, crustaceans, and offal. Can dive up to 15 meters or more and often follows fishing boars in search of food. Feeds mostly at night.


Cory's Shearwater: Generally silent when at sea.

Similar Species

Cory's Shearwater: The Great Shearwater has a distinct black cap, all-black bill, a dark patch on the belly, and dark markings across the underwing coverts. The Fulmar has a shorter, stockier head and body, a thicker and shorter bill, has generally greyer and paler upperparts, and shorter wings.


Belly, undertail coverts, chest, flanks, and foreneck.

Back, rump, hindneck, wings, and crown.
Eye ringX
The circle around the eye formed of feathers that are a different color from the rest of the face.
Flight feathersX
Located on the wing, and collectively called remiges (singular, remex). The long stiff feathers are subdivided into two major groups based on the location and are called primaries and secondaries.
The area between the uppertail coverts and the back of the bird.
4 and 6 letter alpha codesX

The four letter common name alpha code is is derived from the first two letters of the common first name and the first two letters of common last name. The six letter species name alpha code is derived from the first three letters of the scientific name (genus) and the first three letters of the scientific name (species). See (1) below for the rules used to create the codes..

Four-letter (for English common names) and six-letter (for scientific names) species alpha codes were developed by Pyle and DeSante (2003, North American Bird-Bander 28:64-79) to reflect A.O.U. taxonomy and nomenclature (A.O.U. 1998) as modified by Supplements 42 (Auk 117:847-858, 2000) and 43 (Auk 119:897-906, 2002). The list has been updated by Pyle and DeSante to reflect changes reported by the A.O.U from 2003 through 2006.


The Integrated Taxonomic Information System (ITIS) was established in the mid-1990 s as a cooperative project among several federal agencies to improve and expand upon taxonomic data (known as the NODC Taxonomic Code) maintained by the National Oceanographic Data Center (NODC), National Oceanic and Atmospheric Administration (NOAA).

To find the ITIS page for a bird species go to the ITIS web site advanced search and report page at You can enter the TSN or the common name of the bird. It will return the ITIS page for that bird. Another way to obtain the ITIS page is to use the Google search engine. Enter the string ITIS followed by the taxonomic ID, for example "ITIS 178041" will return the page for the Allen's Hummingbird.

Parts of a Standing birdX
Head Feathers and MarkingsX
Parts of a Flying birdX