Seabirds

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Cormorano Comune - Phalacrocorax carbo

Cormorano Comune - Phalacrocorax carbo

Il cormorano comune (Phalacrocorax carbo (Linnaeus, 1758)) è un uccello acquatico della famiglia dei Falacrocoracidi diffuso in tutta l'Eurasia e l'Australasia, ...
Fenicottero Rosa - Phoenicopterus roseus

Fenicottero Rosa - Phoenicopterus roseus

Il fenicottero rosa o fenicottero maggiore (Phoenicopterus roseus Pallas, 1811) è un grande uccello diffuso in Asia, Africa e in Europa meridionale. ...
Gabbiano Reale - Larus michahellis

Gabbiano Reale - Larus michahellis

Il gabbiano reale zampegialle (o gabbiano reale mediterraneo) (Larus michahellis Naumann, 1840) è un uccello caradriiforme appartenente alla famiglia Laridae. ...

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Yellow-legged gull - Archaeological area of Nora - Pula Sardinia - intotheblue.it

Gabbiano Reale – Area archeologica di Nora – Pula Sardegna – intotheblue.it Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations. The first seabirds evolved in the Cretaceous period, and modern seabird families emerged in the PaleogeneUccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

In general, seabirds live longer, breed later and have fewer young than other birds do, but they invest a great deal of time in their young. Most speciesnest in colonies, which can vary in size from a few dozen birds to millions. Many species are famous for undertaking long annual migrations, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean’s surface and below it, and even feed on each other. Seabirds can be highly pelagic, coastal, or in some cases spend a part of the year away from the sea entirely. Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Seabirds and humans have a long history together: they have provided food to hunters, guided fishermen to fishing stocks and led sailors to land. Many species are currently threatened by human activities, and conservation efforts are under way.

giovani e adulti di gabbiano reale europeo - youngs and adults of european herring gull - intotheblue.it

giovani e adulti di gabbiano reale europeo – youngs and adults of european herring gull – intotheblue.it

Adaptations to life at sea

Seabirds have made numerous adaptations to living on and feeding in the sea. Wing morphology has been shaped by the niche an individual species or family has evolved, so that looking at a wing’s shape and loading can tell a scientist about its life feeding behaviour. Longer wings and low wing loading are typical of more pelagic species, while diving species have shorter wings. Species such as the wandering albatross, which forage over huge areas of sea, have a reduced capacity for powered flight and are dependent on a type of gliding called dynamic soaring (where the wind deflected by waves provides lift) as well as slope soaring. Seabirds also almost always have webbed feet, to aid movement on the surface as well as assisting diving in some species. The Procellariiformes are unusual among birds in having a strong sense of smell, which is used to find widely distributed food in a vast ocean, and possibly to locate their colonies.

Salt glands are used by seabirds to deal with the salt they ingest by drinking and feeding (particularly on crustaceans), and to help them osmoregulate. The excretions from these glands (which are positioned in the head of the birds, emerging from the nasal cavity) are almost pure sodium chlorideUccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

With the exception of the cormorants and some terns, and in common with most other birds, all seabirds have waterproof plumage. However, compared to land birds, they have far more feathers protecting their bodies. This dense plumage is better able to protect the bird from getting wet, and cold is kept out by a dense layer of down feathers. The cormorants possess a layer of unique feathers that retain a smaller layer of air (compared to other diving birds) but otherwise soak up water. This allows them to swim without fighting the buoyancy that retaining air in the feathers causes, yet retain enough air to prevent the bird losing excessive heat through contact with water.

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it 

Away from the sea

While the definition of seabirds suggests that the birds in question spend their lives on the ocean, many seabird families have many species that spend some or even most of their lives inland away from the sea. Most strikingly, many species breed tens, hundreds or even thousands of miles inland. Some of these species still return to the ocean to feed; for example, the snow petrel, the nests of which have been found 480 kilometres (300 mi) inland on the Antarctic mainland, are unlikely to find anything to eat around their breeding sites. The marbled murrelet nests inland in old growth forest, seeking huge conifers with large branches to nest on. Other species, such as the California gull, nest and feed inland on lakes, and then move to the coasts in the winter. Some cormorantpelicangull and tern species have individuals that never visit the sea at all, spending their lives on lakes, rivers, swamps and, in the case of some of the gulls, cities and agricultural land. In these cases it is thought that these terrestrial or freshwater birds evolved from marine ancestors. Some seabirds, principally those that nest in tundra, as skuas and phalaropes do, will migrate over land as well.

Fenicotteri Rosa Phoenicopterus roseus Intotheblue.it (Cagliari/Capoterra)

Fenicotteri Rosa Phoenicopterus roseus Intotheblue.it (Cagliari/Capoterra) Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Diet and feeding

Seabirds evolved to exploit different food resources in the world’s seas and oceans, and to a great extent, their physiology and behaviour have been shaped by their diet. These evolutionary forces have often caused species in different families and even orders to evolve similar strategies and adaptations to the same problems, leading to remarkable convergent evolution, such as that between auks and penguins. There are four basic feeding strategies, or ecological guilds, for feeding at sea: surface feeding, pursuit diving, plunge diving and predation of higher vertebrates; within these guilds there are multiple variations on the theme.

Fenicotteri Rosa Phoenicopterus roseus Intotheblue.it (Cagliari/Capoterra)

Fenicotteri Rosa Phoenicopterus roseus Intotheblue.it (Cagliari/Capoterra) Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

Uccelli marini Seabirds mare mediterraneo sea oceano intotheblue.it

https://en.wikipedia.org/wiki/Seabird

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