The elaborate tails of male peafowl indicate sexual selection—because that trait often represents successful breeding. The male feathers’ large size and brilliant colors make it difficult for peacocks that spend most of their time on the ground to hide from predators (peahens have tails that are much smaller and not as colorful). But that is not the feathers’ true “use”—the peacocks’ tails are useful for attracting mates, and it’s been demonstrated that the more eyespot feathers a male has in his tail, the more offspring he will father during mating season.