Cape Verde Shearwater
Encyclopedia
The Cape Verde Shearwater (Calonectris edwardsii), 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
.
as a full species. It was later lumped as a subspecies of Cory's Shearwater
but has since been separated again, by Cornelis Hazevoet in 1995, as a distinct species.
, Branco and Raso, though the species also breeds in smaller numbers on other islands in the archipelago. Though their pelagic 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
zone in Senegal
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.
by fishermen for food, with an estimated 5000 birds taken from their nests on Branco and Raso each year. Numbers have declined because of over-harvesting of young birds and the species is considered to be Near Threatened
.
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...
, a 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...
in the petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...
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...
. It is a breeding 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....
of the Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
of Macaronesia
Macaronesia
Macaronesia is a modern collective name for several groups of islands in the North Atlantic Ocean near Europe and North Africa belonging to three countries: Portugal, Spain, and Cape Verde...
in the Atlantic Ocean
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...
, off the coast of West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
.
Taxonomy
The Cape Verde Shearwater was originally described in 1883 by Émile OustaletÉmile 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...
as a full species. It was later lumped as a subspecies of Cory's Shearwater
Cory's Shearwater
The Cory's Shearwater is a large shearwater in the seabird family Procellariidae.This species breeds on islands and cliffs in the Mediterranean, with the odd outpost on the Atlantic coast of Iberia. The nest is on open ground or among rocks or less often in a burrow where one white egg is laid,...
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, 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 BravaBrava, Cape Verde
Brava is an island in Cape Verde. It is the smallest inhabited island, but at the same time the greenest, of Cape Verde, in the Sotavento group. First settled in the 1540s, its population grew after Mount Fogo on neighbouring Fogo erupted in 1675...
, Branco and Raso, though the species also breeds in smaller numbers on other islands in the archipelago. Though their pelagic 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
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The increased availability in upwelling regions results in high levels of primary...
zone in Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
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.
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 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 harvestedMuttonbirding
Muttonbirding is a seasonal harvesting activity, which may be recreational or commercial, of the chicks of petrels, especially shearwater species, for food, oil and feathers...
by fishermen for food, with an estimated 5000 birds taken from their nests on Branco and Raso each year. Numbers have declined because of over-harvesting of young birds and the species is considered to be Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
.