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Great Cormorant (Phalacrocorax carbo)

This is by far the most widespread member of the Cormorant and Shag family, occurring in eastern North America, Africa, Asia and Australasia, as well as in Europe. Such a wide distribution implies a degree of habitat flexibility and, as far as Europe is concerned, the Great Cormorant shows an interesting dichotomy of breeding site between east and west. In the north-west it is almost entirely a coastal breeding species, building nests on wide cliff ledges and rocky stacks; but in Eastern Europe it is equally at home on large freshwater lakes and wide rivers, nesting up in the trees, to a height of 10m.

Both of its main habitats supply the Great Cormorant with what it needs: sheltered, shallow water with a good supply of fish. This bird is almost entirely a bottom feeder, scouring both bare and vegetated parts of the sea or lake bed. It has a particular fondness for flatfish, but the range of species it takes is quite wide; it depends on what is abundant locally. It has no special preference for size: it will tackle anything from a small sand-eel (Ammodytes) to a large predatory species such as the freshwater pike (Esox lucius). Its battles with eels (Anguilla anguilla) can be spectacular to watch: these long-bodied, wriggly fish are a good but tricky meal, and the birds can spend many minutes attempting to manoeuvre them in the bill so that they can be swallowed. Even when the contest appears to be over, it may not be: eels have been known to wriggle to freedom even when some way down the bird’s gullet.

The Cormorant’s very visible liking for fish sometimes puts it in dispute with anglers and fishery interests. There is no doubt that the Cormorant takes some game fish, and can be a problem where these are artificially concentrated. But the apparent rabid hunger of Cormorants is a myth; they can often acquire what they need for the whole day during just two hunting trips of about half an hour each. The rest of the time they spend preening and lazing around.

Cormorants breed in colonies, usually of a few tens of birds. At the beginning of the season a male lays claim to a nest-site, occupying a suitable ledge and intimidating any intruding rivals with a lunge forward and snake-like twisting of the neck, accompanied by loud calling. Once established, the male attempts to attract a mate with a “wing-waving” display. This involves folding the primary flight feathers behind the secondaries and raising its “blunted” wings up and down rapidly. As the wings are raised the male’s bright white nuptial thigh-patch is revealed enticingly a couple of times a second, in a “now you see me, now you don’t” routine.

The nest is built by both birds, although there is often a clear division of labour, with the male bringing the material – seaweed for coastal nests, sticks and plant fragments inland – and the female arranging it. Whenever either partner arrives at the nest the birds exchange a formal greeting: the attending bird points head and neck up and slightly backwards and makes a gargling call. If the sitting bird is a male it will then go further, leaning its head and neck over its back and touching its tail with its bill closed.