Mate guarding and searching for extra-pair copulations: Decision-making when interests diverge

Extra-pair paternity is widespread among avian species, and large variations in frequency occur both within and among species. These variations result from individual, ecological and phylogenetic influences that impinge upon the strategies used in searching for extra-pair copulations. We used qualitative reasoning to evaluate how the decision-making process for each sex could affect the occurrence of extra-pair paternity and fitness. We demonstrate that the quality of the female's mate influences the female's inclination to search for extra-pair copulations. Also shown is the result that high quality males produce a higher number of within-pair and extra-pair young. Since the interests of males and females converge in certain aspects, both sexes achieved an increment in fitness. The model presented in this paper suggests that the conflict of interests between the sexes is influenced by the willingness of females to engage in extra-pair copulations and by the quality of the male to which the female is mated.