Indian peafowl
The Indian peafowl or blue
peafowl (Pavo cristatus), a large and brightly colored bird, is
a species of peafowl native to South Asia, but introduced
in many other parts of the world.
The male, or peacock, is predominantly blue with a
fan-like crest of spatula-tipped wire-like feathers and is best known for the
long train made up of elongated upper-tail covert feathers which bear
colorful eyespots. These stiff feathers are raised into a fan and quivered in a
display during courtship. Despite the length and size of these covert feathers,
peacocks are still capable of flight. Peahens lack the train, and have a
greenish lower neck and duller
Taxonomy and naming
Carl Linnaeus in his work Systema Naturae in 1758 assigned to the Indian peafowl the technical name of Pavo cristatus (means "crested peafowl" in classical Latin).
The earliest usage of the word in written English is from
around 1300 and spelling variants include pecok, pekok, pecokk, peacocke,
peocock, pyckock, poucock, pocok, pokok, pokokke, and poocok among others. The
current spelling was established in the late 17th century. Chaucer (1343–1400)
used the word to refer to a proud and ostentatious person in his simile "proud
a pekok" in Troilus and Criseyde (Book I, line 210).
The Greek word for peacock was Taos and was
related to the Persian "tavus" (as in Takht-i-Tâvus for the
famed Peacock Throne. The Hebrew
word tuki (plural tukkiyim) has been said to have been derived
from the Tamil tokei but sometimes traced to the Egyptian tekh.
Description
Peacocks
are a larger sized bird with a length from bill to tail of 100 to 115 cm
(39 to 45 in) and to the end of a fully grown train as much as 195 to
225 cm (77 to 89 in) and weigh 4–6 kg (8.8–13.2 lb). The females,
or peahens, are smaller at around 95 cm (37 in) in length and weigh
2.75–4 kg (6.1–8.8 lb). Indian peafowl are among the largest and
heaviest representatives of the Phasianidae. Their size, color and shape
of crest make them unmistakable within their native distribution range. The
male is metallic blue on the crown, the feathers of the head being short and
curled. The fan-shaped crest on the head is made of feathers 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
sides of the head have iridescent greenish blue feathers. The back has scaly
bronze-green feathers with black and copper markings. The scapular and the
wings are buff and barred in black, the primaries are chestnut and the
secondaries are black. The tail is dark brown and the "train" is made
up of 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. The underside is dark glossy green shading into blackish
under the tail. The thighs are buff colored. The male has a spur on the leg
above the hind toe.
Mutations
and hybrids
The adult peahen has a rufous-brown head with a crest as
in the male but the tips are chestnut edged with green. The upper body is
brownish with pale mottling. The primaries, secondaries and tail are dark
brown. The lower neck is metallic green and the breast feathers are dark brown
glossed with green. The remaining under parts are whitish. Downy young are
pale buff with a dark brown mark on the nape that connects with the eyes. Young
males look like the females but the wings are chestnut colored.The most common calls are a
loud pia-ow or may-awe. The frequency of calling increases
before the Monsoon season and may be delivered in alarm or when
disturbed by loud noises. In forests, their calls often indicate the presence of
a predator such as the tiger. They also make many other calls such as a
rapid series of ka-aan..Ka-aan or a rapid kok-kok. They
often emit an explosive low-pitched honk! when agitated.
Mutations
and hybrids
There are several color mutations of Indian peafowl.
These very rarely occur in the wild, but selective breeding has made
them common in captivity. The black-shouldered or Japanned mutation
was initially considered as a subspecies P. c. nigripennis (or even a
species), and was a topic of some interest during Darwin's time. It is
however only a case of genetic variation within the population. In this
mutation, the adult male is melanistic with black wings. Young birds with
the nigripennis mutation are creamy white with fulvous tipped wings.
The gene produces melanism in the male and in the peahen it produces a dilution
of color with creamy white and brown markings. Other variations include the
pied and white forms all of which are the result of allelic variation
at specific loci.Cross between a male green peafowl, Pavo
muticus and a female Indian peafowl, P. cristatus, produces a stable
hybrid called a "spalding", named after Mrs. Keith Spalding, a bird
fancier in California. There can be problems if birds of unknown pedigree
are released into the wild, as the viability of such hybrids and their
offspring is often reduced (see Haldane's Ruleand outbreeding
depression).
Distribution and habitat
The Indian peafowl is a resident breeder across the Indian
subcontinent and is found in the drier lowland areas of Sri Lanka. In
South Asia, it is found mainly below an altitude of 1,800 metres (1.1 mi)
and in rare cases seen at about 2,000 metres (1.2 mi). It is found in
moist and dry-deciduous forests, but can adapt to live in cultivated regions
and around human habitations and is usually found where water is available. In
many parts of northern India, they are protected by religious practices and
will forage around villages and towns for scraps. Some have suggested that the
peacock was introduced into Europe by Alexander the Great, while
others say the bird had reached Athens by 450 BCE and may have been
introduced even earlier. It has since been introduced in many other parts of
the world and has become feral in some areas.
Besides its native habitat, the bird has been introduced
by humans to the United States, Mexico, Honduras, Colombia, Guyana, Suriname, Brazil, Uruguay, Argentina, South
Africa, Portugal, Madagascar, Mauritius, Réunion, Indonesia, Papua
New Guinea, Australia, Croatia (Split, island of Lokrum),
and elsewhere. In isolated cases, the Indian peafowl has been known to be
able to adapt to harsher climates, such as those of northern Canada. The
species has been spotted by Hunters as far north as Huntsville, Ontario,[citation
needed] thriving in its newly adapted northern climate.
Behavior and ecology
Peafowl are best known for the male's extravagant display
feathers which, despite actually growing from their back, are thought of as a
tail. The "train" is in reality made up of the enormously elongated
upper tail coverts. The tail itself is brown and short as in the peahen. The colors
result not from any green or blue pigments but from the micro-structure of the
feathers and the resulting optical phenomena. The long train feathers (and
tarsal spurs) of the male develop only after the second year of life. Fully
developed trains are found in birds older than four years. In northern India,
these begin to develop each February and are moulted at the end of August. The
moult of the flight feathers may be spread out across the year.Peafowl forage on the ground in small groups, known as musters
that usually have a cock and 3 to 5 hens. After the breeding season, the flocks
tend to be made up only of females and young. They are found in the open early
in the mornings and tend to stay in cover during the heat of the day. They are
fond of dust-bathing and at dusk, groups walk in single file to a favorite
waterhole to drink. When disturbed, they usually escape by running and rarely
take to flight.
Peafowl produce loud calls especially in the breeding
season. They may call at night when alarmed and neighboring birds may call in a
relay like series. Nearly seven different call variants have been identified in
the peacocks apart from six alarm calls that are commonly produced by both
sexes.
Peafowl roost in groups during the night on tall
trees but may sometimes make use of rocks, buildings or pylons. In the Gir
forest, they chose tall trees in steep river banks. Birds arrive at dusk
and call frequently before taking their position on the roost trees. Due
to this habit of congregating at the roost, many population studies are made at
these sites. The population structure is not well understood. In a study in
northern India (Jodhpur), the number of males was 170–210 for 100 females but a
study involving evening counts at the roost site in southern India (Injar)
suggested a ratio of 47 males for 100 females.Sexual selection
The colors of the peacock and the contrast with the much
duller peahen were a puzzle to early thinkers. Charles Darwin wrote
to Asa Gray that the "sight of a feather in a peacock's
tail, whenever I gaze at it, makes me sick!" as he failed to see an
adaptive advantage for the extravagant tail which seemed only to be an
encumbrance. Darwin developed a second principle of sexual selection to
resolve the problem, though in the prevailing intellectual trends of Victorian
Britain, the theory failed to gain widespread attention.
The American artist Abbott Handerson Thayer tried
to show, from his own imagination, the value of the eyespots as disruptive
camouflage in a 1907 painting. He used the painting in his 1909 book Concealing-Coloration
in the Animal Kingdom, denying the possibility of sexual selection and arguing
that essentially all forms of animal coloration had evolved as camouflage. He
was roundly criticized in a lengthy paper by Theodore Roosevelt, who wrote
that Thayer had only managed to paint the peacock's plumage as camouflage by
sleight of hand, "with the blue sky showing through the leaves in just
sufficient quantity here and there to warrant the author-artists explaining
that the wonderful blue hues of the peacock's neck are obliterative because
they make it fade into the sky."
In the 1970s a possible resolution to the apparent
contradiction between natural selection and sexual selection was
proposed. Amotz Zahavi argued that peacocks honestly signaled the handicap of
having a large and costly train. However, the mechanism may be less
straightforward than it seems – the cost could arise from depression of
the immune system by the hormones that enhance feather
development.
The ornate train is believed to be the result of sexual
selection by the females. Males use their ornate trains in a courtship display:
they raise the feathers into a fan and quiver them. However, recent studies
have failed to find a relation between the number of displayed eyespots and
mating success. Marion Petrie tested whether or not these displays
signaled a male's genetic quality by studying a feral population of peafowl in Whipsawed
Wildlife Park in southern England. She showed that the number of eyespots in
the train predicted a male's mating success, and this success could be
manipulated by cutting the eyespots off some of the male's ornate feathers. Although
the removal of eyespots makes males less successful in mating, eyespot removal
substantially changes the appearance of male pea fowls. It is likely that
females mistake these males for sub-adults, or perceive that the males are
physically damaged. Moreover, in a feral peafowl population, there is little
variation in the number of eyespots in adult males. It is rare for adult males
to lose a significant number of eyespots. Therefore, females' selection might
depend on other sexual traits of males' trains. The quality of train is an
honest signal of the condition of males; peahens do select males on the basis
of their plumage. A recent study on a natural population of Indian pea fowls in
the Shivalik area of India has proposed a "high maintenance handicap"
theory. It states that only the fittest males can afford the time and energy to
maintain a long tail. Therefore, the long train is an indicator of good body
condition, which results in greater mating success. While train length
seems to correlate positively with MHC diversity in males, females do
not appear to use train length to choose males. A study in Japan also
suggests that peahens do not choose peacocks based on their ornamental plumage,
including train length, number of eyespots and train symmetry. Another
study in France brings up two possible explanations for the conflicting results
that exist. The first explanation is that there might be a genetic variation of
the trait of interest under different geographical areas due to a founder
effect and/or a genetic drift. The second explanation suggests that
"the cost of trait expression may vary with environmental
conditions," so that a trait that is indicative of a particular quality
may not work in another environment.
Fisher's runaway model proposes positive feedback
between female preference for elaborate trains and the elaborate train itself.
This model assumes that the male train is a relatively recent evolutionary
adaptation. However, a molecular phylogeny study on peacock-pheasants shows the
opposite; the most recently evolved species is actually the least ornamented one.
This finding suggests a chase-away sexual selection, in which "females
evolve resistance to male ploys". A study in Japan goes on to
conclude that the "peacocks' train is an obsolete signal for which female
preference has already been lost or weakened".
However, some disagreement has arisen in recent years
concerning whether or not female peafowl do indeed select males with more
ornamented trains. In contrast to Petrie's findings, a seven-year Japanese
study of free-ranging peafowl came to the conclusion that female peafowl do not
select mates solely on the basis of their trains. Mariko Takahashi found no
evidence that peahens expressed any preference for peacocks with more elaborate
trains (such as trains having more ocelli), a more symmetrical
arrangement, or a greater length. Takahashi determined that the peacock's
train was not the universal target of female mate choice, showed little
variance across male populations, and, based on physiological data collected
from this group of peafowl, do not correlate to male physical conditions.
Adeline Loyau and her colleagues responded to Takahashi's study by voicing
concern that alternative explanations for these results had been overlooked,
and that these might be essential for the understanding of the complexity of
mate choice. They concluded that female choice might indeed vary in
different ecological conditions.
A 2013 study that tracked the eye movements of
peahens responding to male displays found that they looked in the direction of
the upper train of feathers only when at long distances and that they looked
only at the lower feathers when males displayed close to them. The rattling of
the tail and the shaking of the wings helped in keeping the attention of
females.
Breeding
Peacocks are polygamous, and the breeding season is
spread out but appears to be dependent on the rains. Peafowls usually
reach sexual maturity at the age of 2 to 3 years old. Several
males may congregate at a lek site and these males are often closely
related. Males at lek appear to maintain small territories next to each
other and they allow females to visit them and make no attempt to guard harems.
Females do not appear to favor specific males. The males display in courtship
by raising the upper-tail coverts into an arched fan. The wings are held half
open and drooped and it periodically vibrates the long feathers producing a
ruffling sound. The cock faces the hen initially and struts and prances around
and sometimes turns around to display the tail. Males may also freeze over
food to invite a female in a form of courtship feeding. Males may
display even in the absence of females. When a male is displaying, females do
not appear to show any interest and usually continue their foraging. The
peak season in southern India is April to May, January to March in Sri Lanka
and June in northern India. The nest is a shallow scrape in the ground lined
with leaves, sticks and other debris. Nests are sometimes placed on buildings and
in earlier times have been recorded using the disused nest platforms of
the white-rumped vultures. The clutch consists of 4–8 fawn to buff
white eggs which are incubated only by the female. The eggs take about 28
days to hatch. The chicks are nidifugous and follow the mother around
after hatching. Downy young may sometimes climb on their mothers' back and
the female may carry them in flight to a safe tree branch. An unusual instance
of a male incubating a clutch of eggs has been reported.
Feeding
Peafowl are omnivorous and eat seeds, insects, fruits,
small mammals and reptiles. They feed on small snakes but keep their distance
from larger ones. In the Gir forest of Gujarat, a large percentage of
their food is made up of the fallen berries of Zizyphus. Around
cultivated areas, peafowl feed on a wide range of crops such as groundnut, tomato, paddy, chili and
even bananas. Around human habitations, they feed on a variety of
food scraps and even human excreta. In the countryside, it is
particularly partial to crops and garden plants.
Mortality factors
Adult peafowl can usually escape ground predators by
flying into trees. Large animals such as leopards, dholes and tigers can
sometimes ambush them however, and in some areas such as the Gir forest,
peafowl are fairly common prey for such formidable predators. Foraging in
groups provides some safety as there are more eyes to look out for predators. They
are also sometimes hunted by large birds of prey such as the crested
hawk-eagle and rock eagle-owl. Chicks are somewhat more prone
to predation than adult birds. Adults living near human habitations are
sometimes hunted by domestic dogs or by humans in some areas
(southern Tamil Nadu) for folk remedies involving the use of "peacock
oil".
In captivity, birds have been known to live for 23 years
but it is estimated that they live for only about 15 years in the wild.
Conservation and status
Indian peafowl are widely distributed in the wild across
South Asia and protected both culturally in many areas and by law in India.
Conservative estimates of the population put them at more than 100,000. Illegal
poaching for meat however continues and declines have been noted in parts of
India. Peafowl breed readily in captivity and as free-ranging ornamental
fowl. Zoos, parks, bird-fanciers and dealers across the world maintain breeding
populations that do not need to be augmented by the capture of wild birds.
Poaching of peacocks for their meat and feathers and
accidental poisoning by feeding on pesticide treated seeds are known threats to
wild birds. Methods to identify if feathers have been plucked or have been
shed naturally have been developed as Indian law allows only the collection of
feathers that have been shed.In parts of India, the birds can be a nuisance
to agriculture as they damage crops. Its adverse effects on crops, however,
seem to be offset by the beneficial role it plays by consuming prodigious
quantities of pests such as grasshoppers. They can also be a problem in gardens
and homes where they damage plants, attack their reflections breaking glass and
mirrors, perch and scratch cars or leave their droppings. Many cities where
they have been introduced and gone feral have peafowl management programmes.
These include educating citizens on how to prevent the birds from causing
damage while treating the birds humanely.
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