ဇင်မံင်

Articles with 'species' microformats
ဇင်မံင် (Pelicans)  (ဗမာ ဌက်ကြီးဝံပို) ဝွံ ဒှ်ဂကူဂစေံဍာ် ဇၞော်ဇၞော် နွံဂၠိုင်ကဵု ဂကူ မလုပ်လၟိဟ် တၞောဝ်ဗဳဇ Pelecanidae ရ။ ဂစေံဇင်မံင် ဂှ် နွံကဵု ခၟူဂၠိင်င် ထိုင်ပါင်ဇၞော်ဇၞော် သွက်ဂွံ ဗက်ရပ်စက၊ ဂိုင်ဍာ် ကိုပ်ကၠာ ဟွံဂွံၚိတ်ဖျေဟ်ရ။

thumb|A brown pelican opening mouth and inflating air sac to display tongue and some inner bill anatomy
right|thumb|American white pelican with knob which develops on bill before the breeding season
right|thumb|An adult brown pelican with a chick in a nest in Chesapeake Bay, Maryland, US: This species will nest on the ground when no suitable trees are available.
thumb|Australian pelican displaying the extent of its throat pouch (Lakes Entrance, Victoria).
Pelicans are very large birds with very long bills characterised by a downcurved hook at the end of the upper mandible, and the attachment of a huge gular pouch to the lower. The slender rami of the lower bill and the flexible tongue muscles form the pouch into a basket for catching fish, and sometimes rainwater, though not to hinder the swallowing of large fish, the tongue itself is tiny. They have a long neck and short stout legs with large, fully webbed feet. Although they are among the heaviest of flying birds, they are relatively light for their apparent bulk because of air pockets in the skeleton and beneath the skin, enabling them to float high in the water. The tail is short and square. The wings are long and broad, suitably shaped for soaring and gliding flight, and have the unusually large number of 30 to 35 secondary flight feathers.

Males are generally larger than females and have longer bills. The smallest species is the brown pelican, small individuals of which can be no more than  and  long, with a wingspan of as little as . The largest is believed to be the Dalmatian, at up to  and  in length, with a maximum wingspan of . The Australian pelican's bill may grow up to  long in large males, the longest of any bird.

Pelicans have mainly light-coloured plumage, the exceptions being the brown and Peruvian pelicans. The bills, pouches, and bare facial skin of all species become brighter before breeding season commences. The throat pouch of the Californian subspecies of the brown pelican turns bright red, and fades to yellow after the eggs are laid, while the throat pouch of the Peruvian pelican turns blue. The American white pelican grows a prominent knob on its bill that is shed once females have laid eggs. The plumage of immature pelicans is darker than that of adults. Newly hatched chicks are naked and pink, darkening to grey or black after 4 to 14 days, then developing a covering of white or grey down.

Air sacs 
Anatomical dissections of two brown pelicans in 1939 showed that pelicans have a network of subcutaneous air sacs under their skin situated across the ventral surface including the throat, breast, and undersides of the wings, as well as having air sacs in their bones. The air sacs are connected to the airways of the respiratory system, and the pelican can keep its air sacs inflated by closing its glottis, but how air sacs are inflated is not clear. The air sacs serve to keep the pelican remarkably buoyant in the water and may also cushion the impact of the pelican's body on the water surface when they dive from flight into water to catch fish. Superficial air sacs may also help to round body contours (especially over the abdomen, where surface protuberances may be caused by viscera changing size and position) to enable the overlying feathers to form more effective heat insulation and also to enable feathers to be held in position for good aerodynamics.

Distribution and habitat 
Modern pelicans are found on all continents except Antarctica. They primarily inhabit warm regions, although breeding ranges extend to latitudes of 45° South (Australian pelicans in Tasmania) and 60° North (American white pelicans in western Canada). Birds of inland and coastal waters, they are absent from polar regions, the deep ocean, oceanic islands (except the Galapagos), and inland South America, as well as from the eastern coast of South America from the mouth of the Amazon River southwards. Subfossil bones have been recovered from as far south as New Zealand's South Island, although their scarcity and isolated occurrence suggests that these remains may have merely been vagrants from Australia (much as is the case today).

Behaviour and ecology

Breeding and lifespan 
 
thumb|Pelecanus occidentalis, Tortuga Bay, Island of Santa Cruz, Galápagos

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