Obligate Brood Parasitism on Neotropical Birds

Abstract

Obligate brood parasites neither build their own nests nor rear their offspring. Instead, they lay their eggs in nests of individuals of other species (hosts) that take care of the parasite’s progeny. Brood parasitism frequently imposes fitness costs on hosts through partial or total reproductive losses. These costs favor the evolution of defenses against parasitism in host populations, which, in turn, may select for counterdefenses in the parasites. As a result, host–parasite interactions can lead to an evolutionary arms race that is manifested in a range of reciprocal adaptations. Because of this interplay between parasites and their hosts, these systems are excellent models for the study of coevolution. In the Neotropics, there are eight brood-parasitic species distributed among three groups: four cowbirds (Icteridae), three New World cuckoos (Cuculidae), and the black-headed duck (Anatidae), the only known precocial brood parasite. In this chapter, we present a compendium of the characteristics and behaviors of these species that can help our understanding on how natural selection can shape the interactions between species.