Robins, blackbirds and nightingales are having to alter the time of their dawn chorus so their efforts are not in vain, a study has found
By Roger Dobson, and Edward Malnick
8:30AM GMT 07 Dec 2014
It is the sound synonymous with the start of a new day. But now, as a result of increased urbanisation and man-made noise levels, birds are having to begin their dawn chorus long before sunrise in order to make themselves heard.
Robins, blackbirds and nightingales are among a series of species which have taken to altering the time of their morning song so their efforts are not in vain, a study has found.
In some cases, birds are starting their dawn chorus two hours before sunrise, potentially putting themselves at risk from predators. A study conducted at five airports found that birds were anticipating the morning rush of planes, which start taking off at 6am, and changing their song times in order to avoid it.
The study builds on research showing that many species had taken to singing louder and at a higher pitch to increase their chances of being heard in noisy cities — although much of the time they are still unable to compete, especially if they are trying to drown out a jumbo jet.
“Our results suggest that birds may anticipate aircraft noise, and show that birds change their behaviour in anticipation of the increase in noise,” said Dr Diego Gil, who led the research. “An earlier dawn chorus is being seen in our cities too because of the joint effects of high ambient noise levels at dawn and continuous artificial lighting over night.’’
Birds use song for attracting mates, defending territories or warning against predators. Songbirds are able to vary the pitch, intensity and content of their calls.
Man-made sounds, the authors said, mask signals between birds, hampering their ability to communicate with each other.