Seabirds
Seabirds are birds that have adjusted to a marine environment. Even though they vary greatly is size and behaviour, most have some similar characteristics due to a similar enviroment and diet. The first 'seabirds' evolved during the Cretaceous period, and modern seabirds emerged in the Paleogene.In general, seabirds live longer, mate later and have fewer young than other birds do, but they invest more time in their young. Most species nest in colonys, which can vary in size from a few dozen birds to millions. Many species undertake large annual migrations, crossing the equator or circumnavigating the Earth in some cases.
The Wandering Albatross, above.
The Wandering Albatross, above.
Classification
There is not any single classification of which species are actually seabirds. In the words of two seabird scientists, "The one common characteristic that all seabirds share is that they feed in saltwater; but, as seems to be true with any statement in biology, some do not."
Terns
Terns are seabirds in the family Sternidae, And have a worldwide distribution. Terns are generally medium to large birds, usually with white or grey plumage and often feature dark marks on the head.They have largish beaks and webbed feet. They are lighter and more streamlined than gulls, and look elegant in flight with long tails and narrow wings.Terns make harsh, single note calls. They range in size from the Least Tern, at 42 g (1.5 oz) and 23 cm (9 inches), to the Caspian Tern, at 630 g (1.4 lbs) and 53 cm (21 inches).
Many terns are long distance migrants,and one Arctic Tern, ringed as a chick (not yet able to fly) on the Farne Islands off the Northumberland coast in eastern Great
Britain in summer 1982, reached Melbourne, in October 1982, a sea journey of over
22,000 km (14,000 statute miles) in just three months from fledging—an average of over 240 km per day, and one
of the longest journeys ever recorded for a bird. Most terns catch fish by diving, but the Marsh terns pick insects off the suface of the water. Terns don't often glide, but a couple of species, (notably the Sooty tern) soar above the sea. Despite having webbed feet, terns avoid swimming (aside from bathing)
Sooty tern in flight, above.
Many terns are long distance migrants,and one Arctic Tern, ringed as a chick (not yet able to fly) on the Farne Islands off the Northumberland coast in eastern Great
Britain in summer 1982, reached Melbourne, in October 1982, a sea journey of over
22,000 km (14,000 statute miles) in just three months from fledging—an average of over 240 km per day, and one
of the longest journeys ever recorded for a bird. Most terns catch fish by diving, but the Marsh terns pick insects off the suface of the water. Terns don't often glide, but a couple of species, (notably the Sooty tern) soar above the sea. Despite having webbed feet, terns avoid swimming (aside from bathing)
Sooty tern in flight, above.
Penguins
Pengiuns are a group of flightless marine birds that live almost completely in the southern henisphere, especially near antarctica.Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans.
The largest species of penguin is the emperor penguin, and the smallest is the little blue penguin (or fairy penguin).
Little Blue penguin, left.
The largest species of penguin is the emperor penguin, and the smallest is the little blue penguin (or fairy penguin).
Little Blue penguin, left.
Sea Eagles
A sea eagle is any of the birds of prey in the genus Haliaeetus[1] in the bird of prey family Accipitridae.
Sea eagles vary in size, from the Sanford's Fish Eagle averaging 2–2.7 kg to the
huge Steller's Sea eagle weighing up to 9 kg
There are eight living species of sea eagles:
White-bellied Sea Eagle (H. leucogaster)
Sanford's Sea Eagle (H. sanfordi)
African Fish Eagle (H. vocifer)
Madagascar Fish Eagle (H. vociferoides)
Pallas's Fish Eagle (H. leucoryphus)
White-tailed Eagle (H. albicilla)
Bald Eagle (H. leucocephalus)
Steller's Sea Eagle (H. pelagicus)
White-Bellied Sea Eagle, above
Sea eagles vary in size, from the Sanford's Fish Eagle averaging 2–2.7 kg to the
huge Steller's Sea eagle weighing up to 9 kg
There are eight living species of sea eagles:
White-bellied Sea Eagle (H. leucogaster)
Sanford's Sea Eagle (H. sanfordi)
African Fish Eagle (H. vocifer)
Madagascar Fish Eagle (H. vociferoides)
Pallas's Fish Eagle (H. leucoryphus)
White-tailed Eagle (H. albicilla)
Bald Eagle (H. leucocephalus)
Steller's Sea Eagle (H. pelagicus)
White-Bellied Sea Eagle, above
By Tom