Urban Blackbirds Produce High-Pitched Songs to be Heard over Traffic Noise

Urban blackbirds sing at higher frequencies to produce loud sounds that can even be heard in traffic noise, reveals a new study detailed in the Proceedings of the Royal Society B journal.

A team of researchers from the Max Planck Institute for Ornithology in Germany studied urban blackbirds in the city of Vienna, Austria, and country blackbirds in the nearby Vienna Woods.

They also studied captive birds raised at the Max Planck Institute in order to determine the correlation between frequency and amplitude of their songs in controlled conditions.

They found that the urban birds prefer to make higher tones at higher amplitudes than their country counterparts. This means that the birds prefer to sing songs at a higher pitch to produce loud sounds and make themselves heard better in city noise.

"By actively selecting high-frequency sounds, the city birds can increase their capacity to sing loudly and in this way counteract the acoustic masking of their song by the ambient noise," Henrik Brumm, the leader of the research team, said in a statement.

With more birds and animals colonizing the cities as their new habitat, there is a need for them to accustom themselves in such urban settings. These birds and animals have adopted various strategies to deal with the increasing noise pollution in their habitats.

For example, urban robins sing later in the night when the traffic noise is less so as to attract their partners for mating and to defend their territories.

Another example is that of grasshoppers which have been found to change the tune of their courtship songs to get heard over the sound of traffic.

A recent study on bow-winged grasshoppers by German researchers has revealed that the insects living in noisy habitats increase the volume of the lower-frequency part of their song to get heard over human-made noise.