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Cory’s shearwater
– Calonectris diomedia borealis –

Cory’s shearwaters (in the family Procellariidae) spend their lives almost entirely at sea. It is a pelagic seabird, that only comes to land to breed. It belongs to the order of tubenoses. Other families within the order of the tubenoses include albatrosses and storm petrels. Tubenoses were named after the two tubular nasal passages on the beak, through which they can excrete salt.

Some tubenosed species can even spray an oily liquid from these tubes at approaching attackers. The beak is long and hooked, with sharp edges. The three front toes of these birds are webbed. Cory’s shearwaters like all other tubenoses are best adapted to long-distance flight, can cover huge distances and weather severe storms. This seabird can be seen in Madeira during the breeding season between March and October.

– General information –

Further names:
Deutsch: Gelbschnabelsturmtaucher

Taxonomy: Class: Aves (birds); Order: Procellariiformes (tubenoses)

Feeding: They mainly feed on fish and squids; also invertebrates and crustaceans.

Range: Globally present; seas and oceans in all climate zones.

Description: Greyish-brown on the back; pale belly and pale markings on the underside of the wings; slightly rounded, long wings; yellowish beak with a dark ring at the tip.

Size of adult animals: At a length of 46 to 60 cm and a wingspan of 112 to 126 cm, Cory’s shearwaters are the largest of the seabirds nesting in Madeira.

Breeding: These birds nest in colonies, mostly in rock caves and crevices in cliff faces. One clutch a year consisting of a single egg (May, June). They are monogamous and always attempt to pair up with their mate from the previous breeding season. They prefer the same nesting site as they used in the previous year. The incubation period is 40 to 60 days. Chicks hatch complete with downy plumage, but grow relatively slowly afterwards. Juveniles stay in the nest for about two to four months. At the beginning, one parent bird is constantly with the chick. When the chick reaches a certain size, both parent birds leave to search for food. When feeding, the parent bird grabs the beak of the chick at a right angle, regurgitates its prey, which the chick then eats. During the breeding season, the vocalisations of the parent birds can be easily heard within a short distance from the nesting sites. In flight, they give out a loud, wailing call. The worldwide biggest colony of Cory’s shearwaters consisting of approx. 13,600 breeding pairs can be found in the uninhabited Savage Islands halfway between Madeira and the Canaries to the South. There, they also nest on the ground (in burrows).