The Indian peafowl (Pavo cristatus), also known as the common peafowl, or blue peafowl, is a species of peafowl native to the Indian subcontinent. While it originated in the Indian subcontinent, it has since been introduced to many other parts of the world. Male peafowl are referred to as peacocks, and female peafowl are referred to as peahens, although both sexes are often referred to colloquially as a "peacock".
The Indian peafowl displays a marked form of sexual dimorphism. The brightly coloured male has a blue coloured head with a fan-shaped crest and is best known for his long train. The train is made up of elongated upper-tail covert feathers with colourful eyespots. These stiff feathers are raised into a fan and quivered in a display during courtship. The peahen is predominantly brown in colour, with a white face and iridescent green lower neck, and lacks the elaborate train. There are several colour mutations of the Indian peafowl including the leucistic white peafowl.
Despite the length and size of the covert feathers, the peacock is still capable of flight. The peafowl lives mainly on the ground in open forests or on cultivable lands where it forages for berries and grains, and also preys on snakes, lizards and small rodents. It makes loud calls, which makes it easier to detect, and are often used to indicate the presence of a predator in the forest areas. It forages on the ground in small groups and usually escapes on foot through undergrowth and avoids flying, though it flies into tall trees to roost.
The function of the Indian peacock's elaborate train has been debated for more than a century. In the 19th century, Charles Darwin found it a puzzle, hard to explain through ordinary natural selection. His later explanation, sexual selection, is widely but not universally accepted. In the 20th century, Amotz Zahavi argued that the train was a handicap, and that males were honestly signalling their fitness in proportion to the splendour of their trains. Despite extensive study, opinions remain divided on the mechanisms involved.
The Indian peafowl is listed as Least Concern on the IUCN Red List. It is the national bird of India and venerated in Hindu and Greek mythology.
The Indian peafowl was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under its current binomial name Pavo cristatus. The genus name Pavo is Latin for "peacock", which came from the Greek word taos derived from Persian tavus, which came from the Tamil word tokei. The specific epitet cristatus is Latin meaning "crested". The species is considered to be monotypic: no subspecies are recognised.
The earliest usage of the word peacock in written English was from the 14th century where Geoffrey Chaucer used the word in a simile "proud a pekok" in his poem Troilus and Criseyde. Various spelling variants included peacock, pacok, pecok, pekok, pokok, and pocok among others.
The Indian peafowl's size, color and shape of the crest make them easily identifiable within their native distribution range. It displays a marked form of sexual dimorphism. A male peafowl or peacock is a larger sized bird with an average bill to tail length of 100–120 cm (40–46 in) and as much as 200–230 cm (78–90 in) to the end of a fully grown train. It weighs 4.1–5.2 kg (9–11.5 lb) and is amongst the heaviest birds in Phasianidae. The male has a metallic blue crown with short and curled, blue-greenish head feathers. It has a fan-shaped crest with bare black shafts and tipped with bluish-green webbing. A white stripe above the eye and a crescent shaped white patch below the eye are formed by bare white skin. The lore, chin and throat are covered with greenish feathers. It has a long blue neck with scaly bronze-green feathers with black and copper markings in the back. The scapular region and wings are made of chestnut colored primary feathers with black secondaries. The tail is dark brown with glossy green chest, buff thighs, and blackish-brown abdomen and tail coverts.
The male is best known for his elongated train, which extend from the rump. The train is made up of elongated upper tail coverts, which are bronze-green train with the outermost and longer feathers ending up with an elaborate eye-spot. The eye-spots consist of a purplish-black, heart-shaped nucleus, enclosed by blue and an outer copper rim, which is surrounded by alternating green and bronze. A few of the outer feathers lack the spot and end in a crescent shaped black tip. The feathers of the train do not have colored pigments and the colorization is a result of the micro-structure of the feathers and the optical phenomena involved. The male has a spur on the leg above the hind toe. The train feathers and the tarsal spur of the male start developing only in the second year of its life. The trains are not fully developed until the age of four. The train feathers of the male Indian peafowl are also moulted every year, usually starting at the end of the monsoon in August or September and are fully developed by February to March. The moult of the flight feathers may be spread out across the year.
The females or peahens, are smaller at around 97 cm (38 in) in length and weigh 2.7–4.1 kg (6–9 lb). The peahen has a rufous-brown head with a crest, whose tips are chestnut colored and edged with green. The upper body is brownish with pale mottling and the primaries, secondaries and tail are dark brown. The lower neck is metallic green with dark brown breast feathers glossed with green and whitish underparts. Both sexes have dark brown eyes, brown colored beak and legs. Young males also resemble the females with chestnut colored primaries.
