City architecture makes birds’ songs shriller

February 23rd, 2012 - 4:31 pm ICT by IANS  

Copenhagen, Feb 23 (IANS) Urban birds sing at a higher frequency than their woodland cousins in order to be heard above the barrier of constant noise produced by traffic, machines and human activity.

Now, researchers at the Universities of Copenhagen (Denmark) and Aberystwyth (Britain) have discovered that besides noise, the architecture of cities also plays a role in altering the songs of birds.

Structures and variations in the cityscape - houses, streets, open spaces and alleys - all serve to reflect and distort noise in differing ways, things that birds must take into account.

“Urban architecture is a crucial determinant of how urban birds sing,” says study co-author Torben Dabelsteen, professor of ecology at Copenhagen. Noise amidst the urban landscape is typically composed of lower frequencies, the journal ‘Public Library of Science One’ reports.

“Now, with the help of controlled sound recordings, we have shown that the higher frequencies in urban birds’ songs are also transmitted across cities when there is not any noise from traffic,” says Dabelsteen.

“This shows that the physical structure of cities must play a considerable role in the heightened frequencies,” explains Dabelsteen, according to a Copenhagen statement.

Birds in the urban environment can easily spot one another, but must do what they can to reduce echoes from buildings and narrow streets in order to penetrate and communicate effectively.

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