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Great Cormorant, Phalacrocorax carbo

The Great Cormorant (Phalacrocorax carbo), known as the Great Black Cormorant across the Northern Hemisphere, the Black Cormorant in Australia, the Large Cormorant in India and the Black Shag further south in New Zealand, 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.

It’s a large black bird, but there is a wide variation in size in the species wide range. Weight is documented from 3.3 pounds to 11.7 pounds, with a typical range from 5.7 to 8.2 pounds. The length can vary from 28 to 40 inches and wingspan from 48 to 63 inches. It has a longish tail and a yellow throat patch. The adults have white thigh patches during the breeding season. In European waters it can be distinguished from the Common Shag by its larger size, heavier build, lack of a crest, plumage without any green tinge and a thicker bill. In eastern North America, it is similarly larger and bulkier than the Double-crested Cormorant, and the latter species has more yellow on the bill and throat. Great Cormorants are mostly silent, but they make various guttural noises while at their breeding colonies.

A very rare deviation of the Great Cormorant is caused by albinism. The Phalacrocorax carbo albino suffers from a loss of eyesight and/or hearing, thus, it rarely manages to survive in the wild.

This is a very frequent and widespread bird species. It feeds in estuaries, on the sea, and on freshwater lakes and rivers. Northern birds migrate south and winter along any coast that is well-supplied with fish.

The type subspecies, P. c. carbo, is found mostly in Atlantic waters and nearby inland areas: on western European coasts and south to North Africa, the Faroe Islands, Iceland and Greenland; and on the eastern seaboard of North America, though in America it breeds only in the north part of its range, in the Canadian maritime provinces.

The subspecies found in Australasian waters, P. carbo novaehollandiae, contains a crest. In New Zealand, it is known as the Black Shag or by its Maori name; Kawau. The syntype is in the collection of the Museum of New Zealand Te Papa Tongarewa.

The 80 to 100 cm long White-breasted Cormorant P. c. lucidus found in sub-Saharan Africa has a white breast and neck. It’s often treated as a full species, Phalacrocorax lucidus.

In addition to the Australasian and African forms, Phalacrocorax carbo novaehollandiae and P. carbo lucidus mentioned above, other geographically distinct species are recognized, including P. c. sinensis, P. c. maroccanus. Some authors treat all these as allospecies of a P. carbo super species group.

This bird mainly breeds on coasts, nesting on cliffs or in trees (which are eventually killed by the droppings), but also increasingly inland.  Three to four eggs are laid in a nest made of seaweed or twigs. It can dive to considerable depths, but it often feeds in shallow water. It often brings prey to the surface. A wide variety of fish are taken: cormorants are often noticed eating eels, but this might reflect the considerable time taken to subdue an eel and position it for swallowing, rather than any dominance of eels in the diet. In British waters, dive times of 20 to 30 seconds are common, with a recovery time on the surface around a 3rd of the dive time.

Many fishermen see the Great Cormorant as a competitor for fish. Because of this, it was nearly hunted to extinction in the past. Thanks to conservation efforts, its numbers increased. Currently, there are about 1.2 million individuals in Europe (based on winter counts. Late summer counts would reveal higher numbers). Growing populations have once again brought the cormorant into conflict with fisheries.

Cormorant fishing is practiced in China, Japan, and elsewhere around the globe. In it, fishermen tie a lie around the throats of cormorants, tight enough to prevent swelling, and deploy them from little boats. The cormorants catch fish without being able to fully swallow them, and the fishermen are able to retrieve the fish by forcing open their mouths, apparently engaging the regurgitation reflex.

In Norway, cormorant is a traditional game bird. Each year ca. 10,000 cormorant are shot to be eaten. In north Norway, cormorants are conventionally seen as semi-sacred. It’s regarded as good luck to have the birds gather near your village or settlement. An old legend states that people who die far out at sea, their bodies never recovered, spend eternity on the island Untrost – which can only occasionally be found by mortals. The inhabitants of Untrost can only visit their homes in the form of cormorants.

Image Caption: Phalacrocorax_carbo. Credit: Miya/Wikipedia (CC BY-SA 3.0)

Great Cormorant Phalacrocorax carbo


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