Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Subfamily: Phasianinae
Genus: Pavo
Species: P. cristatus
Binomial name: Pavo cristatus
Common names: Peacock, Indian Peafowl, Blue Peafowl.

Pavo cristatus is a large and brightly coloured bird of the pheasant family native to South Asia but introduced and semi-feral in many other parts of the world.

The male Pavo cristatus length from bill to tail is 100 to 115 cm and to the end of a fully grown train as much as 195 to 225 cm and weigh 4–6 kg. The tail is dark brown and the "train" is made up by elongated upper tail coverts (more than 200 feathers, the actual tail has only 20 feathers) and nearly all of these feathers end with an elaborate eye-spot. A few of the outer feathers lack the spot and end in a crescent shaped black tip. These stiff and elongated feathers are raised into a fan and quivered in a display during courtship.
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 (fibre-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, while 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 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.
The females known as peahens are smaller at around 95 cm in length and weigh 2.75–4 kg. The female has a mixture of dull green, brown and grey in her plumage. She lacks the long tail of the male,  Male and female both have head crests

In their native land, they are found in groups known as musters that usually have a cock and 3 to 5 hens. They are mainly on the ground in open forest or cultivation where they forage for berries, grains but will also prey on snakes, lizards, and small rodents. They forage on the ground, moving in small groups and will usually try to escape on foot through undergrowth and avoid flying. They will fly up into tall trees to roost. It is a bird that is celebrated in Indian and Greek mythology and is the national bird of India. In New Zealand, they are found in private gardens and in some public parks.

Hear the sound  http://www.junglewalk.com/Asounds/peacock1.wav  Thanks to  JungleWalk.com

Male in courtship.display
[1] 

Photo of the rear of a male in courtship.display.
[2]

A female Pavo cristatus
[3] 

Thanks to Wikipedia for text and information     https://creativecommons.org/licenses/by-sa/3.0/