The study shows a strong link between the change in song and the change in noise.”
Assistant professor in Mason’s undergraduate biology program David Luther
Researchers observed a change in sparrows’ tune during the years of increasing cacophony of car horns and engine rumbles in big cities.
They studied territories of 20 sparrows in the in San Francisco’s Presidio where there is lots of traffic, especially in the morning rush hour when the birds do most of their singing.
Through an iPod speaker, they tracked the white-crowned sparrows’ songs from 1969 and 2005 and observed their divergent reactions.
“The study shows a strong link between the change in song and the change in noise,” said assistant professor in Mason’s undergraduate biology program David Luther.
Experts suggest that as humans raise their voices to be heard when a car speeds past, birds making their homes near busy intersections also have to tweet a little louder.
The change is more than just whistling the same tune and turning up the volume. Most birds stopped singing some old songs because those ditties could not cut through the racket, Luther explained.
Researchers say the birds’ songs need to be heard, not just because they sound pretty but mainly because they help the birds talk to each other, warn away rivals and attract mates.
“If you go into a bird’s territory and play a song from the same species, they think a rival competitor has invaded its territory,” Luther says.
If the rival bird does not hear the song and vamoose, it may come to bird fisticuffs and lead to injury or death.
Researchers believe that many species have not been able to adapt to and live in an urban environment, but the recent finding unveils the ability among white-crowned sparrows.