The handicap principle is a proposed evolutionary force that causes some species to develop traits that, at first glance, lead to a decrease in the organism's adaptability. For example, the bright plumage of male birds makes them more visible and attracts predators, while less brightly colored females are well camouflaged.
However, at the species level, the reproductive success of an organism, that is, the number of its offspring, is more important than its lifespan. This is clearly seen in the example of the pheasant, where females live twice as long as males. But the ability of a male pheasant to reproduce depends not on its lifespan, but on its attractiveness to females.
A male with brightly colored plumage and a large crest demonstrates to the female a high level of fitness, that is, the fact that he survived despite the "handicap" that less conspicuous males had, and therefore the female, who will pass on his genes, especially to daughters who will have camouflaged plumage, ensures their increased fitness.