Brood parasites do not build their own nests but rather lay their eggs in the nests of other individuals (hosts) which then raise the young parasites as their own. Interspecific brood parasitism has evolved independently in several avian lineages, including cowbirds (Molothrus sp.) which occur throughout the Americas. We work in close collaboration with members of the Ecology and Animal Behaviour Lab (Laboratorio de Ecologia y Comportamiento Animal, Prof. Juan Carlos Reboreda) at the University of Buenos Aires, Argentina, to address varied questions on cowbird evolution, behaviour and ecology. Current members of the group involved in work on brood parasitism in cowbirds are Ros Gloag and Alex Kacelnik.