Fig. 2.

Behavioral imprinting maintains host specificity and genetic cohesion of indigobird species but also provides a mechanism for rapid speciation when new hosts are colonized. Male indigobirds mimic the songs of their hosts, whereas females use song cues to choose both their mates and the nests they parasitize. Rarely, females lay in the nest of a novel or alternate host. The resulting offspring imprint on the novel host and are therefore reproductively isolated from their parent population. Indigobird drawing by Karen Klitz.