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Concept
Morus (oiseau)
Résumé
Gannets are seabirds comprising the genus Morus in the family Sulidae, closely related to boobies.
Gannets are large white birds with yellowish heads, black-tipped wings and long bills. Northern gannets are the largest seabirds in the North Atlantic, having a wingspan of up to . The other two species occur in the temperate seas around southern Africa, southern Australia, and New Zealand.
"Gannet" is derived from Old English ganot meaning "strong or masculine", ultimately from the same Old Germanic root as "gander".
Morus is derived from Ancient Greek μωρός moros "stupid" or "foolish" due to lack of fear shown by breeding gannets and boobies, allowing them to be easily killed.
Gannets hunt fish by diving into the sea from a height of and pursuing their prey underwater, and have a number of adaptations:
They have no external nostrils; they are located inside the mouth, instead.
They have air sacs in the face and chest under the skin, which act like bubble wrap, cushioning the impact with the water.
The position of their eyes is far enough forward on the face for binocular vision, allowing them to judge distances accurately.
Gannets can achieve speeds of as they strike the water, enabling them to catch fish at a much greater depth than most airborne birds.
The gannet's supposed capacity for eating large quantities of fish has led to "gannet" becoming a description of somebody with a voracious appetite.
Gannets are colonial breeders on islands and coasts, normally laying one chalky-blue egg. They lack brood patches and use their webbed feet to warm the eggs. They reach maturity around 5 years of age. First-year birds are completely black, and subsequent subadult plumages show increasing amounts of white.
The most important nesting ground for northern gannets is the United Kingdom, with about two-thirds of the world's population. These live mainly in Scotland, including the Shetland Isles. The rest of the world's northern-gannet population nests in Canada, Ireland, the Faroe Islands, and Iceland, with small numbers in France (they are often seen in the Bay of Biscay), the Channel Islands, Norway, and a single colony in Germany on Heligoland.
Source officielle
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