The peacock "tail", is known as a train, consisting not of tail quill feathers, but highly elongated upper tail coverts. These feathers are marked with eyespots, best seen when a peacock fans his tail. The peacock tail produces colours by thin-film interference.

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.