advertising takes a variety of forms in animals. breeding adults often display to attract a mate. breeding males of sexually dimorphic birds, such as peacocks, birds of paradise and bower birds, have elaborate plumage, song, and behaviour. these evolved through sexual selection by females. the males use these features alone or in combination to advertise their presence, and, especially but not only in species with lek mating, to compete with rival males. in a lek, the presence of multiple males advertises and potentially benefits all the males present, so they are both collaborating and competing.