When bombarded by noise pollution, some male birds begin to sing higher tunes, a new study has found, the Discovery News reported. And that tonal shift makes them less attractive to females.

Great tits sing at a higher frequency in noise polluted surroundings. [discovery.com]?

The findings suggest that birds must make difficult trade-offs in urban areas and places where traffic and industrial noises threaten to drown them out.

Either they sing less appealing songs or tones in an effort to rise above the din, or they sing the songs that make them sound appealing at the risk of not being heard at all. Wouter Halfwerk, a behavioral ecologist at Leiden University in the Netherlands said, "It could very well be that noise pollution is interfering with reproductive decisions by females."