Peacocks not such a feast for predators!

THE words “peacock” and “camouflage” are generally considered opposites. But researchers, based in Pennsylvania, now argue that the vivid colours of the flightless bird conceal it from predatory mammals.

To the human eye, the tail feathers of the male peacock stand out like the proverbial sore thumb. However, the retina of the human eye possesses three types of colour receptors, which can detect those colours, enabling humans to distinguish the bird from its duller surroundings.

Peacocks and other birds have four types of receptors, which means they are tetrachromatic.

On the other hand, the eyes of big cats and other natural predators of the peacock contain just two types of visual receptors, making them dichromatic, which is a form of colour blindness.

“Feathers, perceived by humans to be vividly colourful, are often presumed to be equally conspicuous to other mammals, thus presenting an enhanced predation risk,” said Haverford University researcher Suzanne Amador Kane, lead author of the study.

“However, many mammals that prey on adult birds have dichromatic visual systems with just two types of colour-sensitive visual receptors (one sensitive to ultraviolet light), rather than the three characteristics of humans and four of most birds.”

The significant differences between the colour receptors in human and peacock eyes, and those in the eyes of predatory animals, led Suzanne and her colleagues to suggest that the tail feathers of a male peacock announce its presence to females of its kind, without revealing its position to predators. They decided to put their theory to the test and determine if predators were able to detect peacock tails.

The Haverford researchers leveraged multi-spectral imaging and reflectance spectroscopy to simulate the eyes of humans, peacocks, and predatory animals, such as tigers and feral dogs.

They evaluated the brightness, colour and texture of peacock feathers against a green background that represented the natural environment of the animal and its predators.

A scientific paper, published in research journal PLoS ONE, reported that birds could spot the peacock’s tail with ease. In contrast, the predators could barely see the feathers.

In fact, peacock’s tail feathers are not just coloured vibrantly. Their harmonic frequency is lower than the lowest string on a bass guitar, and the sound they make is barely within the lower limit of human hearing.

Furthermore, paying close attention to the feathers when they are moving will reveal that individual sections stay still. Meanwhile, the parts between these “nodes” vibrate at higher speeds, making for an interesting, visual contrast.








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Posted by on Sep 6 2019. Filed under Local News. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

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