“Birds of feathers flock together”…
The British Journal of Animal Behaviour says that when a peacock fans its ornamented train for the ladies during mating season, its feathers quiver, emitting a low-frequency sound inaudible to human ears. Depending on whether they want to attract females from far away or up close, they can change the sound by shaking different parts of their feathers.
These tail feathers, or coverts, spread out in a distinctive train that is more than 60 percent of the bird’s total body length and boast colorful “eye” markings of blue, gold, red, and other hues. The large train is used in mating rituals and courtship displays. It can be arched into a magnificent fan that reaches across the bird’s back and touches the ground on either side. Females are believed to choose their mates according to the size, color, and quality of these outrageous feather trains. (Ref: National Geographic)
The male peachicks don’t start growing their showy trains until about age three. In fact, it’s hard to tell the sex of a peachick because they’re nearly identical to their mothers. At around six months, the males will begin to change color.
What makes the peacock’s feathers so brilliant? Microscopic “crystal-like structures” that reflect different wavelengths of light depending on how they’re spaced, resulting in bright fluorescent colors. Hummingbirds and shimmering butterflies have mastered a similar visual effect on their own wings. (Ref:Mental Floss by Jessica Hullinger)