Cory´s Shearwater

It is a sizable pelagic seabird belonging to the family Procellariidae, distinguished by a wingspan measuring between 112 and 126 cm, an overall body length of 45 to 56 cm, and a body mass ranging from 700 to 900 grams. The plumage shows a soft grayish-brown dorsal coloration, contrasting markedly with an immaculate pure white ventral surface. The underside of the wings is predominantly white, outlined by an evident and slender dusky dark trailing margin. Its most remarkable anatomical feature is its stout, yellowish-buff bill, which displays a distinctive dark smudge at the ungual tip, along with prominent tubular nostrils located along the top of the culmen, functioning in salt excretion. There is no marked sexual dichromatism, although male individuals usually exhibit slightly larger structural measurements, particularly regarding body mass and cranial width.

Geographical distribution: Possesses a breeding range closely centered on the volcanic archipelagos of the northeastern Atlantic Ocean and the wider Macaronesia. Major nesting colonies are located across the Azores, Madeira, the Selvagens Islands, and the Canary Islands, with an additional small breeding enclave occurring on the Berlengas Islands off coastal mainland Portugal. Outside the reproductive period, it performs vast trans-equatorial migrations toward southern latitudes, wintering across productive upwelling zones in the South Atlantic, including offshore zones along Brazil, Argentina, and southwestern Africa influenced by the Benguela Current.

Habitat: Demonstrates strictly pelagic habits throughout most of the annual cycle, inhabiting deep oceanic waters, outer continental shelves, and shelf breaks characterized by strong marine upwellings. During the breeding cycle, it demands precipitous, predator-free insular habitats, relying on volcanic sea cliffs, inaccessible rocky boulder fields, barren islets, and coastal caves exposed to oceanic winds.

Feeding: Forages upon a broad variety of epipelagic organisms, heavily targeting schooling fishes such as sardines, anchovies, and mackerel, along with substantial quantities of squid. Crustaceans and opportunistic fishery discards generated by commercial trawlers and longliners also constitute an important part of its foraging budget. Prey capture is executed mainly through surface-seizing while swimming or by performing shallow plunge-dives, occasionally reaching beneath the surface for several meters.

Behavior: Master of low-energy locomotion, it employs dynamic soaring across oceanic waves, leveraging boundary wind gradients to sustain swift travel without frequent flapping. Pelagic by day, it routinely forms large offshore resting aggregations or rafts outside breeding sites before approaching land at dusk. At the colonies, it displays strictly nocturnal habits, an evolutionary adaptation designed to minimize diurnal predation by large gulls. Its colonial activity is marked by conspicuous acoustic activity, delivering loud, unearthly wailing vocalizations that resonate across the cliffs after nightfall.

Nesting: Exhibits a socially monogamous mating system with lifelong fidelity, frequently returning to the same breeding chamber over consecutive years. The nesting chamber is situated inside burrows dug in loose soil, rock crevices, or beneath large volcanic boulders. Egg-laying occurs during late May, when the female deposits a single white egg. Incubation duties are shared equally by both parents in extended shifts over 52 to 56 days. The chick is provisioned with regurgitated stomach oil and partially digested prey, fledging independently after a growth phase lasting 90 to 105 days.

Conservation status: Classified as a taxon of Least Concern (LC) on the IUCN Red List, supported by its extensive global range and significant overall demographic baseline. Nevertheless, colonial assemblages face persisting threats, including nest predation by invasive alien predators such as rodents and feral cats, severe fledgling fallout triggered by coastal artificial light pollution, and substantial incidental mortality caused by longline bycatch.