The Great Cormorant (Phalacrocorax carbo) is a widespread member of the cormorant family of seabirds. It breeds in much of the Old World and the Atlantic coast of North America.
This is a very common and widespread bird species. It breeds mainly on coasts, nesting on cliffs or in trees (which are eventually killed by the droppings), but also increasingly inland. 3-4 eggs are laid in a nest of seaweed or twigs.
It feeds on the sea, in estuaries, and on freshwater lakes and rivers. Northern birds migrate south and winter along any coast that is well-supplied with fish.
This is a large black bird, 77-94 cm in length with a 121-149 cm wingspan. It has a longish tail and yellow throat-patch. Adults have white thigh patches in the breeding season. In European waters it can be distinguished from the Common Shag by its larger size, heavier build, thicker bill, lack of a crest and plumage without any green tinge.
In eastern North America, it is similarly larger and bulkier than Double-crested Cormorant, and the latter species has more yellow on the throat and bill.
The subspecies found in Australasian waters, P. carbo novaehollandiae, has a crest. In New Zealand it is known as the Black Shag.
The Great Cormorant can dive to considerable depths, but often feeds in shallow water. It frequently brings prey to the surface. A wide variety of fish are taken: cormorants are often noticed eating eels, but this may reflect the considerable time taken to subdue an eel and position it for swallowing, rather than any dominance of eels in the diet. In UK waters, dive times of 20-30 seconds are common, with a recovery time on the surface around a third of dive time.