Cory's shearwater

Calonectris borealis

Photo by Gérard Souty (Espaço Talassa)

Common name:

Order Procellariiformes
Family Procellariidae

This species breeds on the Atlantic archipelagos of the Azores, Madeira and Canary Islands, as well as in small offshore islands on the coast of the Iberian Peninsula. Outside the breeding season they spread as far north as the British Islands, as far west as the coast of North America and as far south as the coasts of South Africa and northern Argentina.


The Cory’s shearwater is 45-56 cm long and has a wingspan of 112-126 cm. These birds weigh 560-1060 g.

They mostly breed in barren offshore islands, occupying cliffs, caves and boulder fields, and forage at sea, both in coastal and oceanic waters.
The Cory’s shearwater mostly feeds on squid, fish (namely boar fish Capros aper, trumpet fish Macrorhamphosus, sauries like Scomberesox saurus and Nanychthys simulans, horse mackerel Trachurus picturatus and chub mackerel Scomber japonicus) and crustaceans. They are regularly attracted to trawlers to feed on offal.
They breed in March-November. They nest in colonies, often with other seabirds, building the nest at the end of a burrow or rock crevice, which may measure up to 1 m in length. There the female lays 1 white egg which is incubated by both parents for 52-62 days, each taking shifts of 6-8 days while the other goes out fishing. The chicks are fed by both parents and fledge 90-105 days after hatching. These birds are very long-lived and typically only start breeding at 7-13 years of age.
IUCN status – LC (Least Concern)
This species has an extremely large range and a global population estimated at 502.000 individuals. The population is believed to be incresing due predominantly to a population recovery at Selvagem Grande, the ost important breeding colony located between Madeira and the Canary Islands. Populations in the Azores are suspected to be declining. Curent threats include introduced mammalian predators, such as the black rat Rattus rattus, poaching of chicks, fledgling mortality caused by artificial lights and by-catch on longline fishing gear. Predator control and regulations to longline fishing are currently under-way in order to minimize these threats.

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