Competitive altruism is a possible mechanism for the persistence of cooperative behaviors, specifically those that are performed unconditionally.
The theory of reciprocal altruism can be used to explain behaviors that are performed by a donor who receives some sort of benefit in the future.
For any given bird, there is an entire flock of potential preeners, who compete in hopes of establishing a beneficial relationship.
McNamara et al. also determined that since a period of searching is required for "mutually acceptable" players to find one another, competitive altruism is more likely to arise in animals with long life spans.
Amotz Zahavi, famous for his work with the altruistic Arabian babbler, suggests that this level of "social prestige" will affect which individuals interact with one another and how they behave.
With competitive altruism, cooperation is considered a trait that provides a signaling benefit, and thus is subject to sexual selection.
Such behavior, called courtship feeding, not only benefits the female, who receives a meal without expending any energy, but also conveys the ability of the male to forage.