Number 86 Happy Peacock

The term peafowl can refer to the two species of bird in the genus Pavo of the pheasant family, Phasianidae. They are best known for the male's extravagant tail, which it displays as part of courtship. The male is called a peacock, the female a peahen. Although commonly used, peacock is an incorrect term to refer to both sexes. The peahen is brown.
The two species are:
Indian Peafowl, Pavo cristatus (Asiatic)
Green Peafowl, Pavo muticus (Asiatic)
The Green Peafowl breeds from Myanmar 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.The male (peacock) Indian Peafowl has beautiful iridescent blue-green or green coloured 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 head crest.
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. Females can also display their plumage to ward off danger to her young or other female competition.
The Green Peafowl is very different in appearance to the Indian Peafowl. The male has a more green and even gold plumage than the Indian Peafowl and even more brilliant color. The wings are black with a sheen of blue. The crest is of a very different shape and is tufted. The head is usually greenish in color, although the speculated new race/species P. (muticus) annamensis is said to have a bluer head than many other peafowl.
Unlike the Indian Peafowl, the Green Peahen is very similar to the male, only having shorter upper tail coverts and less iridesence. It is very hard to tell a juvenile male from an adult female. The female of the speculated race/species annamensis has an incredibly golden sheen, but that is exhibited in both sexes.
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 color is created by the periodic structure, and the other is a created by a Fabry-Perot interference peak from reflections off the outermost and innermost boundaries of the periodic structure.
Such interference-based structural color 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.