A uniquely magnificent bird revered for its dazzling display, the peacock has long been associated with power, strength, and divinity. In its native India where it is the national bird, the peacock represents the flow of time.
According to Hindu cosmogony, the peacock was created from a feather of the mythological bird, Garuda—an eagle-like Hindu demigod and vehicle mount for the principal deity Vishnu.
The peacock is a central figure in the ethnic Yazidi religion, believed to be the manifestation of god and leader of the archangels. In Greek mythology, the peacock was a symbol of royalty, linked to the goddess Hera.
The Romans saw the peacock as a symbol of immortality. Peacock symbolism even found its way into early Christianity, forever captured in ancient paintings, mosaics, and funerary art.
For centuries, the exquisite beauty of the peacock has captured humankind, transcending borders and cultural bounds. Its otherworldly plumage exhibition has drawn this pheasant-like bird into the realms of religion and spirituality. But what is the biological purpose of this spectacular showmanship?
Sexual Dimorphism in Peafowls
The name “peacock,” which is the term for the male peafowl, has been widely adopted for both sexes, given the male’s mystique and charisma. The female, or “peahen” is oft overshadowed by the peacock’s conspicuous attributes.
She is herself, however, extraordinary—her plumage, albeit modest in comparison, compliments her demure and elegant demeanor.
Of the three species of peafowls, the Indian peafowl is the most widely known. Its nearest relative, the green peafowl native to Southeast Asia and the Indochinese Peninsula, is endangered due to widespread deforestation, severely fragmenting its habitat.
Across the ocean, the near-threatened Congo peafowl, endemic to the Congo Basin, is the only species with a natural range outside of Asia.
The Indian peahen is mostly brown with a cream-white belly and iridescent scalloped coverts enveloping her long, slender neck. Like the male, she too has an upright, fanned crest comprised of thin feather-tipped shafts, although hers are drab in coloration.
More notably, the female lacks the long, colorful train for which the species is revered.
The striking male has an electric blue-green, iridescent plumage. His buff-colored wings have black and white barring with black secondaries and chestnut primaries.
Did you know?
Both species of Asian peacocks do not display their actual tail feathers, but rather the long, upper tail coverts, which form the glamorous train. A peacock’s train comprises more than two-hundred plumes, most of which bear the iconic eyespot or ocellus.
Unlike the Indian peafowl, the male and female green peafowl are similar in appearance, both having a shimmery green neck, dark wings, and an upright, blue-green crest. Both sexes have striking, green upper tail coverts, but only the male’s extends into a long, ornamented train.
The plumage of the Congo peafowl is the least impressive but nonetheless distinctive, especially in its native Africa, where it is the only peafowl species. Both sexes have russet-colored heads and shimmery-green backs.
The male has black body plumage, an electric blue mantle and breast, and a white crest. Females are russet-brown with brown crests. Interestingly, the Congo peacock lacks the upper tail coverts that make up the classic train of its Asiatic cousins, and instead raises its tail feathers during display.
Peacocks and their Fanciful Plumage
Many theories exist around the evolution of the peacock’s plumage. Among bird species, plumage plays an important role in mate selection. We know that in many species, male birds are typically brighter and more colorful compared to their female companions.
This sexual dimorphism can be most conspicuous during the breeding season. But how does their plumage inform the process?
Survival of the Prettiest
Much like how natural selection is based on the fight to survive, sexual selection is based on the drive to reproduce. According to Darwin’s theory on sexual selection, physical embellishments like the peacock’s tail pose significant advantages in the mating game.
Simply put, if peahens prefer peacocks with more ornamented trains, then those peacocks will mate more frequently and have more offspring. The next generation of peacocks will, on average, have more elaborate trains, having inherited the genes for such, and they, in turn will have better mating success than their less decorated rivals.
Peacock trains thus become more impressive with each generation, and courtship signaling grows more extraordinary and complex as each generation of peacocks must level up to compete for the attention of the generation’s peahens.
A study conducted among a feral population in England in the late 80s showed that peahens indeed prefer males with more ornamented trains, supporting Darwin’s theory.
The Perils of Polygamy
The degree of sexual dimorphism varies between species, with some species having little to no differences between the sexes. Many monogamous birds are similar in appearance, such as eagles, cranes, and most parrots. Species that mate for life are relieved of the pressure to find a new mate each season.
Polygamous species on the other hand, have had to up their game over the millennia, and many have evolved striking plumage and vivid displays. The peacock is among the most decorated bird species. But is there more to the dance than mere aesthetics?
An Eye for Quality
A popular model for sexual dimorphism in birds asserts that ornate plumage in males may be a sign of quality genes that come with virility, disease resistance, and better health—traits that females would want to pass on to their offspring.
Research shows that peacocks bearing longer, more extravagant trains do, in fact bear markers associated with genetic diversity. However, peahens do not appear to specifically choose males with longer trains. One study found that the number of eyespots in the train plays a key role, as it not only predicted a male’s mating success but also led to healthier offspring and increased survival ability.
Intimidation Tactics
Natural selection has also had its play in the evolution of the peacock’s train. Males with larger, more extravagant trains have been observed to have better mating success and demonstrated higher survivability against predators—a quality that no doubt comes in handy for a ground-feeding species.
While this could be attributed to underlying causes, such as the disease prevalence among less decorated males, there are also superficial benefits to extravagance. Together with the peacock’s vociferous call, its larger-than-life, brilliantly colored train with menacing ocelli creates quite the fearsome warning display against predators as well as rivals.
Peacocks are highly territorial animals, especially during the breeding season.
They will fight each other to defend the territory and protect their mating rights, mates, and food sources. Peahens also display their tail feathers when they feel threatened or to signal danger, and they too will fiercely defend the nest.
The Way to a Peahen’s Heart
Some researchers have linked the evolution of certain secondary sexual characteristics to mimicry, suggesting that attractive qualities of male birds may have evolved to mimic favored food sources, with the male peacock’s train effectively mimicking a blueberry bush—the color of the eye spots resembling blueberries.
This concept of mimicry in mate selection is covered by the Needing Aesthetics theory, which explains an organism’s drive to approach things that are essential to its survival, such as food and shelter.
The Dance Off
Mate selection among peafowl takes place during lekking ceremonies, whereby a group of male birds gather to strut their stuff in competitive courtship displays. The peacocks compete for prime spots on the dance floor and attract peahens to the lek with loud courtship calls.
The display begins upon a peahen’s arrival and entails the peacock raising his tail and fanning the plumes of his train at a forty-five-degree angle in relation to the sun in order to invoke the full iridescent qualities of the colors in an ostentatious exhibition.
Peahens must select their mates by evaluating the exhibit, paying careful attention to every detail, in order to effectively judge the overall condition of the displaying male. Specific elements such as vibrance, color contrast, iridescence, and symmetrical arrangement of the eyespots appear to influence a peacock’s mating success, possibly even more so than train size.
Good Vibrations
Once a peacock has piqued the interest of a female, he begins rattling his train, serenading his prospective mate with sound waves undetectable to the human ear. The vibrations are picked up by the peahen through the plumes of her crest, which are tuned to receive these “love notes” that communicate his suitability.
The Cost of Beauty
A notable benefit for female birds having drab coloration is that it enables them to lay low when nesting, offering protection for mother, eggs, and hatchlings.
Camouflage and cryptic coloration are specifically seen in females of species that are more vulnerable when nesting, such as ducks and weavers—the males of which, with their brilliant plumage could make eye-catching targets for predators.
The peacock is not just boldly colored but also carries a weighty, six-foot appendage. Some research has shown that the peacock’s long, heavy train doesn’t necessarily inhibit his ability to take off or fly short distances.
Still, it may pose obvious disadvantages for escaping predators. Consequently, even the inconvenience of having to lug around the excess baggage proves beneficial when it comes to mate selection, since only the fittest males could survive bearing lengthy, ornamented trains.
The handicap principle posits that the peacock’s train is an honest indicator for survivability, raising a more decorated peacock’s appeal as a suitable mate.
What Peahens Want
Despite the many theories surrounding its evolution, there are several opposing theories and findings. A Japanese study found that peahens do not necessarily select mates solely on the basis of their trains.
Over the seven years of observations, there was no evidence that the peahens within the population preferred peacocks bearing longer, more elaborate trains with more eyespots or a more appealing arrangement, indicating that a female’s choice of mate may vary across different environments and ecological conditions.
Conclusion
Whatever its evolutionary drivers, the peacock’s elaborate plumage has certainly succeeded in capturing the interest of humankind. The downside of bearing such bedazzling adornments is the hefty price tag that accompanies humanity’s reverence.
Both male and female peafowl are subjected to poaching and poisoning for their precious plumes, despite the existence of sustainable and humane means of harvesting the feathers as they shed. In India, hunting and killing of peafowl is prohibited under the Wildlife Protection Act, and exports of the feathers are banned.
Methods have also been discovered to distinguish between plucked and shed feathers. However, animal rights groups are calling for a total ban due to the loophole created by the domestic market.
This majestic species has been admired, revered, and studied for centuries, yet we are still unraveling the mysteries behind the peacock’s flamboyant display of nature’s extravagance.
