Birds living in urban areas sing louder and faster than their rural counterparts, according to a new study.
The changes in the songs is to help their calls to be heard over the howl of traffic and the wind, says a report published in the latest issue of Nature.
The songs of ‘Great tits’ (parus major) living in ten major European cities were compared with the tunes from those living in nearby forests.
All the city dwellers were found to make shorter, faster and more high-pitched sounds, researchers reported.
“Quick, repetitious trills pass better through high wind and the low frequencies of traffic noise,” explained Hans Slabbekoorn from Leiden University in the Netherlands. “Whereas low, slower sounds transmit better through dense vegetation.”
Changing one's tune to be heard over background noise is not a new phenomenon, he said. Urban nightingales (Luscinia megarhynchos) have been shown to raise their volume when their surrounding is noisy.
Also birds that live near the crash of a waterfall have a higher frequency call than those residing in quieter woodland, the report added. Slabbekoorn's team previously showed that Great tits in the city of Leiden had different tunes depending on whether they lived in quiet or bustling areas.
The ability of the male bird to adapt his repertoire can make a big difference to his life; male birds use sound to defend their territory and to attract females, the report said.
“If the birds still used low-frequency sounds in the city, they would lose the ability to communicate,” explained Slabbekoorn. “Leaving out lower frequencies seems critical to the bird's ability to thrive,” he concluded.