The Observer reports this weekend on various studies that show urban songbirds are increasingly streesed from competing in their communications with the noises humans are producing. Noise from traffic, both road and air and from industrial estates are causing songbirds to sing louder, increase their frequencies, reduce their diversity of range in their song and move at times to singing at night.
The result is that songbirds in cities are damaging their health, exposing themselves to predators and weakening their gene pool by trying to be heard above the din of urban life. Their songs are becoming more chaotic and less diverse, which makes them less attractive to female birds and damages their mating opportunities.
‘The difference between urban and rural birdsong is becoming so great that the two groups could now be unable to communicate, leading to inbreeding and a weakened gene pool,’ said Dr Sue Anne Zollinger, of the University of St Andrews, who has studied the impact of environmental noise on birds’ song learning and development.
Another study of the dawn chorus of nightingales found that birds in Berlin sang up to 14 decibels louder than their counterparts in the forest. The highest volume occurred on weekday mornings. A further group found that great tits in European cities sang at a higher frequency than birds in the country, so that they could be heard above the rumble of cars, lorries and industry.
Henrik Brumm, from the Max Planck Institute for Ornithology in Germany, agreed. ‘This is a hot topic and one we are only just beginning to understand,’ he said. Research has linked noise pollution to a drop in the number of orioles, cuckoos, great reed warblers and house sparrows.
Mark Constantine, author of The Sound Approach to Birding and founder of the Sound Approach database, the fourth-largest natural sound archive in the world, said: ‘Birdsong is used as an indicator of quality of life and has been proved to reduce our blood pressure. When we live in the centre of large, urban areas, we get more stressed and it’s extremely good to have birdsong around us. The impact on humans of birdsong is massive. It harms us, as well as the birds, if their songs become simpler, shriller and louder.’
Certainly I noticed on holidaying recently in a seaside village on the south coast of England the fantastic dominance of birdsong within the village soundscape. It was a refreshing change from the noise pollution found within large metropolitan areas. Certainly planes are one of the worst culprits but trucks are by far the number one enemy.