Comparing vocal structures of the parasitic and nonparasitic groups in Cuculinae

Background: Avian brood parasitism is a breeding strategy in which brood parasites lay their eggs in the nest of other species. This behavior is closely related to aspects of the biological evolution of the parasitic species such as reduced female body size and plumage color polymorphism. However, not much is known whether it is associated with the evolution of vocalization. Methods: We collected samples of the typical male calls of 67 species belonging to the sub-family Cuculinae. Using the calls, we measured five acoustic parameters for each samples to test the differences in vocal structures between parasitic and nonparasitic species. To control for potential phylogenetic effects, we also performed phylogenetic independent contrast analyses. Results: We found that vocal structures were relatively similar among the parasitic species with a tendency to simple and low-frequency calls. In addition, harmonic structures were observed more frequently in the nonparasitic group. Conclusions: Overall, these results support the idea that brood parasitic behavior with associated ecological conditions may play a role in vocal evolution, a better understanding of which may greatly improve our knowledge of vocal diversification in non-oscine birds.