The city birds who are battling to be heard

Birds living in cities are damaging their health by singing louder and at higher frequencies to compete with the urban din.

Their song is becoming more chaotic and could harm their vocal cords and hearing, according to research.

Some birds are singing at night instead of in the day to avoid competing with traffic and other city noise. But this makes them more vulnerable to attack from night-time predators.


Birds such as this thrush are damaging their health by singing louder to keep up with the city din

It also leads to stress and exhaustion, because the birds need to be awake in daylight hours to feed.

Birds sing to warn of danger, attract a mate and mark out their territory.

Dr Sue Anne Zollinger, of the University of St Andrews, has studied the impact of environmental noise on birdsong.

She said: 'By trying to sing over the sound of the city, birds are risking vocal injury because they're using more pressure to sing loudly, while also singing at higher frequencies to try to counteract the low rumble of traffic noise.

'All this effort puts the same strain on a bird's vocal cords as when a human tries to shout to be heard in a noisy pub - but the birds are doing it all day, every day.'

This pressure also means birds have less control over the sound they produce. Their songs could deteriorate in quality, becoming 'rough-sounding'. Dr Zollinger added: 'This could have serious implications on how fit and attractive they're perceived to be by females.

'Even when they manage to mate, however, their female offspring will prefer males who sing in the same lower-quality way, which will eventually lead to complete isolation between different groups and inbreeding.'

Birds most at risk of genetic separation are those most talented at adapting their song, such as starlings, song thrushes, nightingales, robins and marsh warblers.

But scientists also fear some birds are not flexible enough to adapt to the urban racket. Research has linked noise pollution to population crashes in orioles, cuckoos and house sparrows.

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