ScienceDaily (Nov. 20, 2012) — Do birds change their tune in response to urban noise? It depends on the bird species, according to Dr. Alejandro Ariel Ríos-Chelén from the Universidad Nacional Autónoma de México and colleagues. Their work shows that while some birds do adapt their songs in noisy conditions by means of frequency changes, others like the vermilion flycatchers adapt their song by means of changes in song lengths.
The work is published online in Springer's journal, Behavioral Ecology and Sociobiology.
Birds use their songs during social interactions to attract females and repel intruders. Factors affecting acoustic communication, such as urban noise, may therefore impair breeding success. Research to date has shown that several songbird (or oscine) species like robins, nightingales and blackbirds, adapt their song in response to noise. This is done in order to improve acoustic communication in noisy conditions. However, little work has been done on the more tropical sister group of the oscines, the sub-oscines, which includes the vermilion flycatcher.
Rios-Chelén and team investigated whether male vermilion flycatchers adapted their song under noisy conditions in the same way as their less tropical sister group. They recorded the songs of 29 territorial vermilion flycatcher males in different parks and urban areas of Mexico City. They registered noise levels at different moments of both the pre-dawn and dawn chorus, measured song length, and counted the total number of elements in the birds' song to assess song versatility.