Merak / Peafowl

Sunday, July 25, 2010
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The term peafowl can refer to the two species of bird in the genus Pavo of the pheasant family, Phasianidae. The African Congo Peafowl is placed in its own genus Afropavo and is not dealt with here. Peafowl are best known for the male's extravagant tail, which it displays as part of courtship. The male is called a peacock, and the female a peahen,[1] although it is common to hear the female also referred to as a "peacock" or "female peacock". The female peafowl is brown or toned grey and brown. The two species are:
The Indian Peafowl is a resident breeder in the Indian subcontinent. The peacock is designated as the national bird of India and the provincial bird of the Punjab (Pakistan).
The Green Peafowl breeds from Burma east to Java. The IUCN lists the Green Peafowl as vulnerable to extinction due to hunting and a reduction in extent and quality of habitat.

Plumage


The male (peacock) Indian Peafowl has iridescent blue-green or green colored plumage. The so-called "tail" of the peacock, also termed the "train," is not the tail quill feathers but highly elongated upper tail coverts. The train feathers have a series of eyes that are best seen when the tail is fanned. Both species have a crest atop the head.
The female (peahen) Indian Peafowl has a mixture of dull green, brown, and grey in her plumage. She lacks the long upper tail coverts of the male but has a crest. The female can also display her plumage to ward off female competition or danger to her young.
The Green Peafowl is different in appearance from the Indian Peafowl. The male has green and gold plumage and has an erect crest. The wings are black with a sheen of blue.
Unlike the Indian Peafowl, the Green Peahen is very similar to the male, only having shorter upper tail coverts and less iridescence. It is very hard to tell a juvenile male from an adult female.
Many of the brilliant colours of the peacock plumage are due to an optical interference phenomenon, Bragg reflection, based on (nearly) periodic nanostructures found in the barbules (fiber-like components) of the feathers.
Different colours correspond to different length scales of the periodic structures. For brown feathers, a mixture of red and blue is required: one colour is created by the periodic structure, and the other is a created by a Fabry–Pérot interference peak from reflections off the outermost and innermost boundaries of the periodic structure. White peafowls are sometimes bred.
Such interference-based structural colour is especially important in producing the peacock's iridescent hues (which shimmer and change with viewing angle), since interference effects depend upon the angle of light, unlike chemical pigments.

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