Cheating, Infanticide, and Egg-Dumping

Abstract

Abstract Infidelity is rife in monogamous pairs of blue-footed boobies. Before egg-laying, paired female and male blue-footed boobies court extra partners, and half of them copulate with extra partners, both sexes preferring to do so when their own partners are absent, especially females. Eleven percent of broods include a chick not sired by the resident male, and such chicks are more common in nests where the habitat structure and social environment of the colony facilitate liaisons. Male infidelity is rewarded by additional low-cost offspring and facilitates males’ partner-switching. The mixed evidence suggests that female infidelity may have evolved to enable partner-switching, facilitate parasitic egg-dumping in the extra male’s nest, secure better genes for the female’s offspring, assure fertilization when her partner is infertile, or earn concessions to offspring from extra males. Males defend against infidelity by guarding their partners, disrupting copulations, and destroying eggs they may not have sired.