The Cape Verde shearwater (''Calonectris edwardsii''), or cagarra locally, is a medium-large

shearwater Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and are pelagic outside the breeding season. Description These tub ...

, a

seabird Seabirds (also known as marine birds) are birds that are 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 enviro ...

in the

petrel Petrels are tube-nosed seabirds in the bird order Procellariiformes. Description The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group (all except the albatross f ...

family

Procellariidae The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes (or tubenoses), which als ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the Cape Verde

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arc ...

Macaronesia Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic islands ...

in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, off the coast of

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, M ...

Taxonomy

The Cape Verde shearwater was originally described in 1883 by

Émile Oustalet Jean-Frédéric Émile Oustalet (24 August 1844 – 23 October 1905 Saint-Cast) was a French zoologist.Hellmayr CE (1906). "Emile Oustalet bituary. ''Ornithologische Monatsberichte'' 14 (4): 57-59Scan Oustalet was born at Montbéliard, in the de ...

as a full species. It was later lumped as a subspecies of

Cory's shearwater Cory's shearwater (''Calonectris borealis'') is a large shearwater in the seabird family Procellariidae. It breeds colonially of rocky islands in the eastern Atlantic. Outside the breeding season it ranges widely in the Atlantic. It was formerl ...

but has since been separated again, by Cornelis Hazevoet in 1995, as a distinct species.

Description

The Cape Verde shearwater has a slim, dark

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Plac ...

, with head and upperparts darker than Cory's. The flight is more typically shearwater-like than Cory's, with stiffer and more rapid wing beats. The overall appearance, compared with Cory's, is of a smaller, slimmer and more angular bird.

Distribution

The shearwaters breed only within the Cape Verde Islands. The largest colonies are on the islands of

Brava Brava or La Brava may refer to: Geography *Brava, Cape Verde, a volcanic island *Brava, Costa Rica, an island of Costa Rica (Isla Brava) *Costa Brava, a coastal area Mediterranean of northeast Spain * Barawa, a town in Somalia commonly known as ' ...

, Branco and Raso, though the species also breeds in smaller numbers on other islands in the archipelago. Though their

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

distribution and movements are not well known, they are regularly seen around the islands in the breeding season. After the breeding season they disperse and may sometimes be seen in the

upwelling Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted surface water. The nut ...

zone in

Senegal Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣𞤭 ...

ese waters, where about 10% of the population has been recorded in October. There have been records from the South Atlantic as well as one from the eastern coast of North America.Curtis,W.F. (1994). Further South Atlantic records. ''Sea Swallow'' 43: 19-28.

Behaviour

Breeding

Following a three-month absence, the mature birds arrive at their island breeding colonies in late February and March, where they nest in cliff hollows, on offshore rocks, and under large boulders. Females lay a single

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

and incubation takes place from May to July, with the chicks fledging from late September to November. Following fledging, all birds stay at sea until the next breeding season.

Feeding

As with other shearwaters, all food is taken at sea and consists of small fish, squid and other marine organisms.

Status and conservation

The total population was estimated in 1993 to number about 20,000 mature individuals (10,000 breeding pairs). Although the species is notionally protected, the chicks are harvested by fishermen for food, with an estimated 5000 birds taken from their nests on Branco and Raso each year.BirdLife International: Cape Verde Shearwater: Threats
/ref> Numbers have declined because of

over-harvesting Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term ap ...

of young birds and the species is considered to be

near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify f ...

.BirdLife International. (2008). Species factsheet: ''Calonectris edwardsii''. Downloaded from on 10/1/2009.

References

External links

Magikbirds: Cape Verde shearwaterAvibase: Cape Verde shearwaterARKive: Cape Verde shearwater
{{Taxonbar, from=Q181323 Calonectris Endemic birds of Cape Verde

Cape Verde shearwater The Cape Verde shearwater (''Calonectris edwardsii''), or cagarra locally, is a medium-large shearwater, a seabird in the petrel family Procellariidae. It is Endemism in birds, endemic to the Cape Verde archipelago of Macaronesia in the Atlantic ...