Diving and Fishing Birds

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Picture of a group of Neotropic Cormorants
Picture of a group of Neotropic Cormorants near Piriapolis, Uruguay

Diagram of bill of Cormorant
Diagram of Cormorant's Bill

Picture of Cormorant Fishing
Picture of a Neotropic Cormorant Flying on a Fishing Expedition

The birds known as Cormorant and Shag together form the Phalacrocoracidae family of birds within the order Pelecaniformes.

Cormorants and Shags are middle to large, heavybuilt sea-birds, who usually have dark plumage and a skin coloration in the face generally around the eyes and extending to the bill, which varies from bright blue to orange, red or yellow.  Their size is between 45 cm to 1 meter in length.  They have long, supple necks, and a rather long, wedge-shaped tail.  The bill is long, thin and curved with a sharp hook at the endpoint.

They are usually coastal birds, although some colonize inland waters. For example the Great Cormorant (Phalacrocorax carbo) breeds far from the coast. With the exception of the central Pacific islands,  Cormorants and Shags are common worldwide.  They and are particularly plentiful in New Zealand and the western coast of the USA - cormorants in those areas are among the most splendidly dressed in their dark feathered outfits.

Fishing Abilities of the Cormorant

All cormorants are good fishers, eating around 500 grams of fish a day.  They can dive under water for more than a minute, reaching depths of around 10 metres.  Below the water they swim by using paddle movements of their feet which have a webbed membrane between the  four toes.  After fishing, cormorants dry their plumage by spreading their wings wide in the sun. This attitude is so typical for cormorants that even inexperienced birdwatchers can recognize these birds from a distance. The habit is to be attributed to the fact that their plumage is not water resistant, a characteristic unusual for water birds, but which allows them to sink and dive with ease.

Humans have themselves in the past made use of the diving and fishing abilities of the cormorant.  This traditional method of fishing can still be observed in Inuyama in Yangshuo on the borders of the river Li in China.

Social and Nesting Habits

Cormorants are social birds and usually live in colonies, located on small stony islands, cliffs or trees.  When a flock of cormorants are flying together, they adopt a V formation, similar to many other large birds.

The nest is usually a piled up construction made from grasses, seaweed and wood. The two to four eggs, which a clutch of eggs normally contains, have a pale-blue coloring. The incubation period lasts about 27 to 30 days and both parents birds take part in incubating the eggs.  The chicks receive their food from the throat of the parents birds. After 5 to 6 weeks the cormorant chicks leave their nest, and become independent after 10 to 12 weeks.  Normally only one brood is produced in a year.

Cormorants and Humans

As well as being utilised by humans for their fishing abilities, another benefit that the cormorant provides for humans, mainly in Peru, is the bird's excrement, known as guano.  This is used in Peru as an agricultural fertiliser.

The poet Milton in Paradise Lost book IV line 196 compared satan sitting on the Tree of Life to a cormorant.   It may be that the Cormorant's unusual way of spreading its wings out to dry after a dive brought this similie to Milton's mind.   However, when they are normally at rest with their wings closed they have been compared in a more gentle way to a row of black colored bottles.  


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