A songbird’s ability to tell the difference between bird song early in life is genetically determined, according to a study of two flycatcher species published this week in Nature Ecology & Evolution.

Songbirds discriminate between songs of their own and other closely related species from an early age. However, the mechanism underlying song discrimination is unknown and several factors, such as early experience, maternal effects, and genetic background might contribute.

David Wheatcroft and Anna Qvarnstrom swapped embryos in nests of pied and collared flycatchers, two songbird species that can be found in the Baltic island of Oland. The authors found nestlings responded more strongly to songs of their own species, even when they were raised by adults of the other species. This suggests that early song discrimination does not depend on early song experience. The authors then crossed the two species to generate hybrids and found that hybrid nestlings responded better to pied flycatcher songs, irrespective of their maternal species. This indicates that early song discrimination is genetically determined and does not rely on a strong influence from maternal species.

The genetic basis of song discrimination in these flycatchers implies genetic divergence between such closely related species with overlapping geographic ranges, and suggests a potential role of song discrimination in the formation of new and distinct species.