handicap principle
the idea that nonhuman animals use high-cost honest signals to demonstrate their potential as mates. The long, loud, continuous song of songbirds, the tails of peacocks, and the loud roars of howler monkeys are all energetically costly and make the caller conspicuous to predators. However, if these “handicaps” provide accurate information about the condition or quality of the animal, superior individuals will become preferred mates, and the conspicuous and costly traits will be maintained in future generations.