Many birds have bright, ornamental plumage.
Most often it is displayed by the male of the species, who is believed to use the plumage to attract females. The female may select male breeding partners on the basis of this feather advertisement, perhaps assessing their health. According to evolutionary theory, it behooves the female to choose a strong, healthy male to be the father of her chicks, not only because the male helps to feed them but also because the chicks will carry dad's healthy genes. Another possible form of plumage selection has been studied by biologists in Canada. American coots are birds that live in the marshes of western North America.