The African black coucal (Centropus grillii) and the white-browed coucal (Centropus superciliosus) breed in the damp and swampy grasslands of sub-Saharan Africa. In some places the two closely related species share the same habitat, feed on the same prey, and breed during the same time, often in close proximity to one another. But they show extreme differences in their mating system.
The white-browed coucal is socially monogamous, which means that one female and one male form a pair. They share parental duties equally and raise their young together. In the black coucal sex-roles are reversed: Females are much bigger than males. Each female sings and defends a large territory, in which she pairs with up to four males simultaneously (polyandry). In contrast, the males rarely sing, but are responsible for incubating and feeding the young all by themselves.
What are the physiological mechanisms that determine the differences in behavior of those two species? Which ecological and evolutionary factors have led to the dramatic differences in behavior and life-history of these two closely related species? To approach these mechanistic and evolutionary questions we study individually color-marked coucals that are in addition equipped with radio-transmitters in the Usangu Plains, Tanzania.