Sunday, September 11, 2011

Albatross sea bird

History
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes (the tubenoses). They range widely in the Southern Ocean and the North Pacific. They are absent from the North Atlantic. They feed on squid, fish and krill by either scavenging, surface seizing or diving. Albatrosses are colonial, nesting for the most part on remote oceanic islands, often with several species nesting together. Pair bonds between males and females form over several years, with the use of 'ritualised dances', and will last for the life of the pair.

Numbers of albatrosses have declined in the past due to harvesting for feathers, but today the albatrosses are threatened by introduced species such as rats and feral cats that attack eggs, chicks and nesting adults; by pollution; by a serious decline in fish stocks in many regions largely due to overfishing; and by long-line fishing.

Albatrosses, along with all Procellariiformes have a need to lower their salt content due to drinking sea water. All birds have an enlarged nasal gland at the base of the bill, above their eyes. This gland is inactive in species that don't require it, but the Procellariiformes do require its use. Scientists are uncertain as to its exact processes, but do know in general terms that it removes salt that forms a 5% saline solution that drips out of their nose or is forcibly ejected in some birds.

The adult plumage of most of the albatrosses is usually some variation of dark upper-wing and back, white undersides, often compared to that of a gull. the species range from the Southern Royal Albatross which is almost completely white except for the ends and trailing edges of the wings in fully mature males, to the Amsterdam Albatross which has an almost juvenile-like breeding plumage with a great deal of brown, particularly a strong brown band around the chest.

Diet and Breading
fish, crustaceans, and offal although they will also scavenge carrion and feed on other zooplankton. It should be noted that for most species, a comprehensive understanding of diet is only known for the breeding season, when the albatrosses regularly return to land and study is possible. The importance of each of these food sources varies from species to species, and even from population to population; some concentrate on squid alone, others take more krill or fish. Of the two albatross species found in Hawaii, one, the Black-footed Albatross, takes mostly fish while the Laysan feeds on squid.
Light-mantled Albatrosses regularly dive to feed, and can dive to below 12 m.The use of dataloggers at sea that record ingestion of water against time (providing a likely time of feeding) suggest that albatross predominantly feed during the day.

they are found on exposed headlands with good approaches from the sea in several directions, like the colony on the Otago Peninsula in Dunedin, New Zealand. Many Buller's Albatrosses and Black-footed Albatrosses nest under trees in open forest. Colonies vary from the very dense aggregations favoured by the mollymawks (Black-browed Albatross colonies on the Falkland Islands have densities of 70 nests per 100 m²) to the much looser groups and widely spaced individual nests favoured by the sooty and great albatrosses. All albatross colonies are on islands that historically were free of land mammals. Albatrosses are K-selected with regard to their life history, meaning they live much longer than other birds, they delay breeding for longer, and invest more effort into fewer young. Albatrosses are very long lived; most species survive upwards of 50 years, the oldest recorded being a Northern Royal Albatross that was ringed as an adult and survived for another 51 years, giving it an estimated age of 61. Young non-breeders will attend a colony prior to beginning to breed, spending many years practising the elaborate breeding rituals and "dances" that the family is famous for. Birds arriving back at the colony for the first time already have the stereotyped behaviours that compose albatross language, but can neither "read" that behaviour as exhibited by other birds nor respond appropriately. After a period of trial and error learning, the young birds learn the syntax and perfect the dances. This language is mastered more rapidly if the younger birds are around older birds.

The repertoire of behaviour involves synchronised performances of various actions such as preening, pointing, calling, bill clacking, staring, and combinations of such behaviours (like the sky-call). When a bird first returns to the colony it will dance with many partners, but after a number of years the number of birds an individual will interact with drops, until one partner is chosen and a pair is formed. They then continue to perfect an individual language that will eventually be unique to that one pair.

Albatross sea bird in flying
Albatross sea bird with baby
Albatross sea bird pics

In all albatross species, both parents incubate the egg in stints that last between one day and three weeks. Incubation lasts around 70 to 80 days (longer for the larger albatrosses), the longest incubation period of any bird. It can be an energetically demanding process, with the adult losing as much as 83 g (2.9 oz) of body weight a day.

After hatching, the chick, which is semi-altricial is brooded and guarded for three weeks until it is large enough to defend and thermoregulate itself. During this period the parents feed the chick small meals when they relieve each other from duty. After the brooding period is over, the chick is fed in regular intervals by both parents. The parents adopt alternative patterns of short and long foraging trips, providing meals that weigh around 12% of their body weight (around 600 g (21 oz)). The meals are composed of both fresh squid, fish and krill, as well as stomach oil, an energy-rich food that is lighter to carry than undigested prey items. This oil is created in a stomach organ known as a proventriculus from digested prey items by most tubenoses, and gives them their distinctive musty smell.

Albatrosses brood young chicks until they are large enough to thermoregulate.Albatross chicks take a long time to fledge. In the case of the great albatrosses, it can take up to 280 days; even for the smaller albatrosses, it takes anywhere between 140 and 170 days. Like many seabirds, albatross chicks will gain enough weight to be heavier than their parents, and prior to fledging they use these reserves to build up body condition (particularly growing all their flight feathers), usually fledging at the same weight as their parents.

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