The Brood parasitism Research Group studies various aspects of brood parasitism, a rare reproductive strategy in vertebrates. We focus on 1) obligate interspecific brood parasitism in the common cuckoo (Cuculus canorus), which parasitises Acrocephalus warblers, and 2) conspecific brood parasitism in the barn swallow (Hirundo rustica). We explore the ecological and evolutionary mechanisms of these reproductive strategies, especially the various morphological, physiological and behavioural adaptations that have evolved in both parasites and hosts. Finally, we aim to identify factors that promote the origin and maintenance of a parasitic reproductive strategy and the antiparasitic adaptations that it gives rise to. Alongside video-recording brood parasitism in situ, we also undertake extensive bird catching for colour-ringing and collection of genetic data. We also use up-to-date methods that simulate avian visual perception of colours and patterns in order to study the impact of visual signals (e.g. mimetic eggs of brood parasites) on host behaviour (e.g. egg recognition).