Abstract
In many bird species, males commonly feed their mates during the breeding season. Feeding by males to females has been studied from the behavioral ecological perspective such as sexual role, sexual conflict, and the maintenance of the pair bonding. Previous studies have identified various functions of feeding by males to females that are related to individual fitness. These studies have helped us to understand the relationship between males and females in their breeding. In this review, I examine hypotheses explaining the function of feeding by males to females during the breeding period: before pair formation, from pair formation to egg-laying, and during the incubation period. I also discuss the evolution of this behavior. I introduce the following hypotheses in this review: (1) female choice before pair formation, (2a) female nutrition, (2b) copulation in exchange for food, (2c) mate appraisal, and (2d) pair bond from pair formation to egg laying, and (3a) female nutrition, (3b) mate appraisal, and (3c) pair bond, during the incubation period.
