London, Mar 29 (UNI) If you are one of those who wait for a cock's crowing to leave bed, be ready to hear the wake up call in the middle of the night.
Experts have warned that noise pollution was forcing urban birds to change their crooning time from dawn and sing at night in order to be heard.
Researchers claimed that urban clamour was drowning out their chirping. It led to some birds changing the way they communicated, while many others had given up singing at their traditional times altogether.
The report published in New Scientist magazine found that robins nesting in areas that were noisy during the day were more likely to sing at night than those in quieter regions.
The analysis suggested that the creatures altered the times at which they sang to be heard above the city din.
Lead researcher Richard Fuller said subtle effects of urbanisation were forcing birds to adapt this behaviour.
The birds might become more stressed if they were forced to spend the night singing rather than sleeping.
The constant rumble of cars, trucks and factories is masking the sound of the dawn chorus which males use to attract mates.
Birds also sang to warn of danger and mark out their territory.
The noise pollution, however, drowns out noises made by approaching predators and blocks alarm calls, leaving birds open to danger, experts say.
Many believe that urban noise could eventually lead to the emergence of new species. As male birds use songs to attract mates, those that can sing above the urban din - or distinguish birdsong from the background noise of cars and factories - are more likely to breed successfully.
Some scientists believe the European blackbird has already diverged into separate urban and rural subspecies with different body shapes and life histories.
A 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.
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