Have you ever had to raise your voice on a noisy city street just to talk to the person next to you?

It turns out that some birds may actually do something similar to cope with a noisy environment.

Songbirds that live near loud traffic sing at a higher pitch than their relatives in quieter neighborhoods, say researchers from Leiden in the Netherlands.

The Dutch scientists studied the great tit, a common European bird. Great tits are related to chickadees in North America. They sing a few different kinds of songs. One goes: "tee-tah, tee-tah," like a bicycle pump.

To study how environmental conditions affect bird songs, the researchers recorded the voices of 32 male great tits in various places around Leiden. They also took measurements of background sound throughout the city.

Birds in quiet neighborhoods sang at a lower pitch compared to birds in louder parts of the city, measurements showed. All that noise from cars, trucks, leaf blowers, and other machines seems to drown out lower tones, the researchers speculate.

It's important for male great tits to make themselves heard because their songs help them establish territories. Noise pollution might also affect other creatures in unknown ways.

So, next time you find yourself shouting over the sound of a jackhammer, listen closely. Birds and squirrels might have their own way of shouting back at you!—E. Sohn