Cory’s Shearwater, Calonectris diomedea

This is a large shearwater in the seabird family of Procellariidae. This species breeding takes place on islands and cliffs in the Mediterranean. Their nests are on open ground or among rocks, or less often they are in a burrow, where one white egg is laid, and is visited at night to lessen the predation of the large gulls. In late summer and autumn, most of the birds migrate into the Atlantic as far north as the south-western coasts of Great Britain and Ireland. They then return to the Mediterranean in February. The largest colony of Cory’s Shearwaters is in Savage Islands, Madeira.

When this bird flies, it takes long glides and always bows its wings and angles its back slightly. The shearwater is recognizable by its size, at 45-56 cm in length and with a 112-126 cm wingspan. It has brownish-grey upper parts, white under parts, and a yellowish bill.

There are two subspecies, the Mediterranean subspecies C. d. diomede, and the Atlantic subspecies C. d. borealis. Their appearances are closely similar, but the Atlantic race is larger, with a bill that is stouter. They are best recognized by the pattern of the underwing. Because they are very distinct, sometimes they are regarded as separate species.

Cory’s Shearwater feeds on fish, mollusks, and offal. When searching for prey, they can dive as deep as 50ft or more. These birds were named after the American ornithologist Charles B. Cory.

Image Caption: Cory’s Shearwater bottom. Credit: TomAllmendinger/Wikipedia (CC BY-SA 3.0)