Indian peafowl

• 1. A Feather That Made Darwin Sick

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  The Indian peafowl, known scientifically as Pavo cristatus, once made Charles Darwin feel physically ill. Writing to the botanist Asa Gray, he confessed that "the sight of a feather in a peacock's tail, whenever I gaze at it, makes me sick!" The cause of his distress was a bird native to the Indian subcontinent, also called the common peafowl or the blue peafowl. It has since been introduced to many other parts of the world. Its glittering tail has been argued over for more than a century, and opinions are still divided. Why would a bird grow something so showy and so costly? How does it live from one day to the next, on the ground and among predators? And why have so many cultures found a place for it in their stories?

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• 2. What's in a Name

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  In 1758, the Swedish naturalist Carl Linnaeus formally described the bird in the tenth edition of his Systema Naturae. He gave it the name it still carries, Pavo cristatus. The genus name Pavo is simply Latin for peacock. That Latin word came from the Greek taos, which was derived from the Persian tavus, which in turn came from the Tamil word tokei. The second half of the name, cristatus, is Latin for crested. Scientists treat the species as monotypic, which means that no subspecies are recognised.

  Everyday vocabulary is looser than the scientific kind. Strictly speaking, the male is a peacock, the female is a peahen, and peafowl covers both. In casual speech, people often call either sex a peacock.

  The English word has a long paper trail. In the 14th century, Geoffrey Chaucer used it in his poem Troilus and Criseyde, in the simile "proud a pekok". Spellings wandered widely in those early years, and variants included pacok, pecok, pokok and pocok. The crest that gave Linnaeus his second name turns out to be only the start of the male's decoration.

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• 3. Anatomy of a Spectacle

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  The peacock's metallic blue crown carries a fan-shaped crest made of bare black shafts tipped with bluish-green webbing. A white stripe above each eye and a crescent-shaped white patch below it are formed by bare skin. His long neck is blue, his back is covered in scaly bronze-green feathers with black and copper markings, and his wings combine chestnut primaries with black secondaries. He is a large bird, and he ranks among the heaviest members of the pheasant family, Phasianidae.

  The famous train is not made of true tail feathers. It grows from the rump and consists of greatly elongated upper tail coverts, bronze-green in colour. Each long outer feather ends in an eyespot built in layers. A purplish-black, heart-shaped nucleus sits at the centre, wrapped in blue and then a copper rim, with alternating bands of green and bronze outside that. A few outer feathers have no spot and end in a crescent-shaped black tip. The feathers contain no coloured pigment at all. Their colour comes from their microscopic structure and the way it handles light.

  The male takes years to reach this form. His train feathers and the spur on his leg above the hind toe begin to develop only in his second year. The train is not fully grown until he is four. Every year the train feathers are moulted, usually starting at the end of the monsoon in August or September, and they are fully regrown by February or March. The start of shedding varies by place. It begins between the end of July in Bandipur National Park and the end of October in eastern Tamil Nadu. The flight feathers moult more gradually, spread across the year.

  The peahen is smaller, at around 38 centimetres in length, and far plainer. She has a rufous-brown head with a crest tipped in chestnut and edged in green, a white face, and a metallic green lower neck. Her upper body is brownish with pale mottling, her breast is dark brown glossed with green, and her underparts are whitish. Both sexes have dark brown eyes, beaks and legs. Young males look like females, with chestnut primaries.

  Breeders have made several colour mutations common in captive birds, including the leucistic white peafowl. One of them, the black-shouldered form, was once treated as a subspecies or even a separate species, which was given the name P. nigripennis. Darwin presented firm evidence that it was a domestic variety. This mattered to him, because a distinct wild species would have contradicted his theory of slow modification by natural selection in the wild. In this variety the adult male is melanistic with black wings, while the young are creamy white with fulvous-tipped wings. The same gene dilutes the colour of females, who show creamy white and brown markings. The pied and white forms arise from allelic variation at specific loci.

  Crosses between a male green peafowl, Pavo muticus, and a female Indian peafowl produce a stable hybrid known as a Spalding. It is named after Keith Spalding, a bird fancier from California. Releasing birds of unknown pedigree into the wild can cause outbreeding depression, because hybrids and their offspring often have reduced viability, as Haldane's rule predicts.

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• 4. Range and Daily Life

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  From the Indus valley in the north-west to Assam in the north-east, the Indian peafowl is found across most of India. It lives from the Himalayas in the north to the southern tip, with the marshlands of the Sunderbans in East India as the exception. It reaches elevations of 5000 feet in the north and 6000 feet in the mountains of the south. In Sri Lanka it mostly occupies the drier lowlands. Forests, small hills and bushy areas near water suit it, but it also uses cultivated land and lives in a semi-domesticated state around human homes.

  Introduced birds have turned feral in some places. The bird was supposedly brought to Europe by Alexander the Great, although it may have arrived earlier, and it had reached Athens by 450 BCE.

  A group of peafowl is called a muster. A typical muster has a single peacock and three to five peahens. After the breeding season, flocks tend to consist only of females and young. The birds feed in the open in the early morning, rest under cover through the heat of the day, and are often seen dust-bathing at dusk. At night they roost in tall trees, though sometimes they use rocks or buildings. They arrive at roosts around dusk and call often before settling into position.

  Despite its size, the bird can fly, but it rarely does. When disturbed, it usually runs away through the undergrowth. If it does take off, it relies on regular, slower wingbeats rather than gliding.

  The diet is wide. Groups often walk in single file to a waterhole for a drink. The peafowl eats grass, seeds, flowerbuds, fruits, insects and small reptiles, and it also preys on snakes, lizards and small rodents. Near human settlements it takes food scraps and even human excreta. Crops it eats include peanut, tomato, paddy, chili pepper and bananas. In the Gir forest, a large share of its diet is Zizyphus berries. In the Anaikatty Hills, the diet is mostly plant matter, with less than 9 percent made up of ants, termites, grasshoppers, beetles and earthworms. Two peafowl were once seen pecking at and teasing a cobra, though they did not kill it.

  The bird's genome has also been read. The first whole-genome sequencing found 15,970 protein-coding sequences. It also found less repetitive DNA, at 8.62 percent, than in the chicken genome, at 9.45 percent. Studies suggest the population went through at least two bottlenecks, four million years ago and 450,000 years ago, which sharply cut its effective population size.

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• 5. Calls and Courtship

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  The most common call is a loud pia-ow or may-awe, and it becomes more frequent before the monsoon season arrives. Other calls include a rapid run of ka-aan, ka-aan and a quick kok-kok. When agitated, the bird gives an explosive, low-pitched honk. Alarmed birds raise loud calls, and these often signal a predator such as a tiger in the forest. A bird may call at night, and its neighbours may answer in a relay. Researchers have identified nearly seven call variants, plus six alarm variants that both sexes produce.

  The monsoon rains set the breeding calendar, and the peacock is polygamous. Several males, often closely related, gather at a lek site. Each keeps a small territory beside the others and lets females visit. None of them tries to guard a harem, and females do not favour particular males.

  The courtship display is the famous part. The peacock raises his train into an arched fan and quivers it. His wings are held half open and drooped, and from time to time he vibrates the long feathers, producing a ruffling sound. He faces the peahen at first and may turn around to show her the tail. Display sites are usually open and raised, such as fallen trees, large rocks and even rooftops. The peacock also freezes over a piece of food to invite a peahen to come closer, a form of courtship feeding. He often displays when peahens are present and sometimes when they are not. During all this, peahens seem to take little interest and generally carry on foraging.

  Nests are often shallow scrapes on the ground, lined with leaves, sticks and other debris. The birds also nest in crevices in buildings and in disused vulture nests. The female lays a clutch of three to eight oval eggs with polished, thick shells marked by pits and pores. Their colour ranges from pale white to buff or reddish-brown. Males take no part in hatching or rearing the young, though one isolated case of a male incubating a clutch has been reported. Females incubate for about 28 to 30 days.

  The chicks are nidifugous, meaning they follow their mother after hatching rather than staying in the nest. Downy young sometimes climb onto her back, and she may carry them in flight to a safe branch. The peahen's apparent indifference to the show is exactly what makes the question of the train so hard to settle.

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• 6. The Handicap Debate

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  Darwin saw no adaptive advantage in the extravagant tail, which looked like a mere encumbrance. His answer was the principle of sexual selection, though not everyone accepted it. In 1907, the American artist Abbott Handerson Thayer showed in a painting that the eyespots could form a kind of disruptive camouflage. In his 1909 book Concealing-Coloration in the Animal Kingdom, he rejected sexual selection and argued that nearly all animal coloration had evolved as camouflage. Theodore Roosevelt criticised the theory.

  In the 1970s, Amotz Zahavi offered a possible resolution. He argued that the peacock honestly signals his quality through the handicap of a large and costly train. The mechanism may be less simple than that, and the cost may lie in hormones that boost feather growth while also weakening the immune system. Ronald Fisher's runaway model proposed instead a positive feedback loop between female preference and the train itself. But that model assumes the train is a fairly recent adaptation. A molecular phylogeny study found the opposite, because the most recently evolved species is the least ornamented. That finding points toward chase-away sexual selection, in which females evolved resistance to the male ploy.

  Field studies have pulled in different directions. A study of the feral population at Whipsnade Wildlife Park in southern England found that the number of eyespots predicted a male's mating success. Cutting eyespots off some males changed that success. Chicks fathered by more ornamented males also weighed more, which suggested better survival. Recent studies, however, have found no link between displayed eyespots and mating success.

  A seven-year study of free-ranging peafowl went further. It found no evidence that peahens preferred trains with more eyespots, a more symmetrical layout or greater length. It concluded that the train is an obsolete signal whose appeal has been "lost or weakened". It suggested that females in the earlier study may have mistaken the trimmed males for sub-adults or for injured birds. It also noted that adult males in a feral population rarely lose many eyespots, so eyespots may not form a basis for selection at all. A British research team replied that other explanations had been overlooked, and that female choice might differ under different ecological conditions.

  A 2010 study of a natural population in northern India proposed a "high maintenance handicap". Only the fittest males can afford the time and energy to keep a long train, so train length indicates good body condition. Train length correlated positively with diversity in the major histocompatibility complex in males, yet females did not seem to use it to choose. A study in France offered two explanations. One was genetic variation in the trait across regions, caused by a founder effect or genetic drift. The other was that "the cost of trait expression may vary with environmental conditions", so a signal may work in one place and fail in another.

  A 2013 study tracked the eye movements of peahens watching displays. Peahens looked at the upper train only from a long distance, and looked only at the lower feathers when a male displayed close by. The rattling of the tail and the shaking of the wings helped keep their attention.

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• 7. Predators, Pests and Protection

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  Up to 23 years is how long an Indian peafowl is known to live in captivity. In the wild, the estimate is only about 15 years. Adults are hard to catch, since they can usually flee into trees. Even so, tigers, leopards, hyenas, dholes and golden jackals ambush them. Smaller peafowl are sometimes taken by large birds of prey such as the changeable hawk-eagle and the rock eagle-owl. Chicks are more vulnerable than adults. Adults near homes may be hunted by domestic dogs or by people. Foraging in groups gives some safety, since more eyes watch for danger.

  People pose threats of their own. Poaching for meat and feathers is one, and accidental poisoning from pesticide-treated seeds is another. Some birds are also hunted for use in folk remedies. For centuries the species has been part of the agricultural ecosystem, where it spreads seeds and eats pests such as insects and small rodents. But it can cut rice yields by 40 percent through the damage it does. In cities, peafowl damage garden plants, attack their own reflections and break glass and mirrors, and they perch on and scratch cars and leave droppings.

  The species is protected both culturally and by law in India and Sri Lanka. Indian law allows the collection only of feathers that have been shed, so methods have been developed to tell plucked feathers from naturally shed ones. Several cities have set up peafowl management programmes that teach residents how to prevent damage while treating the birds humanely. Sanctuaries in India include Adichunchanagiri Hills, Choolannur Pea Fowl Sanctuary and Viralimalai Bird Sanctuary. The bird also breeds readily in captivity, and zoos, parks and bird fanciers keep breeding populations around the world.

  A conservative estimate in 2002 put the population at more than 100,000. The exact number is unknown, but it is not thought to be falling. The IUCN Red List classes the species as Least Concern. Its protection owes as much to belief as to law, and those beliefs are the last thing left to explore.

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• 8. A Bird of Myth and Heraldry

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  In Hindu tradition, the war god Kartikeya rides an Indian peacock named Paravani as his vahana, or divine mount. Krishna is often shown with a peacock feather on his crown. The Ramayana tells of Indra, head of the devas, who could not defeat the asura king Ravana and sheltered under a peacock's wing. He later blessed the bird with a "thousand eyes" and with fearlessness toward serpents. Another story says Indra was cursed with a thousand ulcers and turned into a peacock with a thousand eyes, until Vishnu removed the curse. In Buddhist philosophy, the bird stands for wisdom. The Indian peafowl is the national bird of India, and it appears in temple art, poetry, folk music and tradition across the subcontinent.

  The bird's body has been used as medicine. Many uses of its parts as an antidote to snake venom have been documented in Ayurveda and other folk remedies. Folklore also holds that peahens are impregnated through the tears of the peacocks.

  Farther west, Greek mythology explains the origin of the plumage in the tale of Hera and Argus. Melek Taus, the main figure of the Yezidis, is commonly depicted as a peacock. A golden peacock is regarded as a symbol of Ashkenazi Jewish culture and features in folktales and songs in Yiddish. Peacock feathers were buried with Viking warriors.

  Medieval Europe gave the bird a martial role. Knights took a "vow of the peacock" and decorated their helmets with its plumes. In Robin Hood stories, the archer uses arrows fletched with peacock feathers. Great estates and gardens kept the birds in menageries and as ornaments. In 1526, whether peacocks counted as wild or domestic fowl was thought important enough for Cardinal Wolsey to summon all the English judges. Their opinion was that peacocks are domestic fowl.

  Heraldry used the bird often, usually facing the viewer with its tail displayed, a pose called "in his pride". Peacock tails shown in isolation are rare in British heraldry but frequent in German systems. Feathers and motifs appear in rituals, ornament, architecture, coinage and textiles. They also appear in modern logos, such as those of the NBC television network and SriLankan Airlines.

  The language has absorbed the bird too. In English, "peacocking" describes pride or a great deal of attention paid to clothing. In Australia, the word once meant something quite different, the practice of buying up the best pieces of land so as to render the surrounding lands valueless.

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