Birds have developed a creative coping mechanism to communicate in urban environments.
A large part of being a bird is singing -- and it's not just to pass the time. Bird songs are often sung to attract the attention of other birds -- specifically, those of the opposite sex.
But as it turns out, urban birds, including those populating the streets of D.C., have been changing their bird songs that they often use to "pick up" their prospective mates. The dull roar of city life is affecting how birds sing their songs, according to Peter Marra, conservation scientist at the Smithsonian Conservation Biology Institute.
"Urban noise changes the low frequency, or the low-pitch sounds that birds produce," says Marra. "So birds with lower songs have to sing differently. Those low-pitch songs decline in five out of six species we looked at because those sounds compete. So birds have changed their songs to higher frequency songs."
For instance, the pitch of the Carolina wren in an urban setting has lost a lot of its low frequency sound, whereas the Carolina wren in a rural setting has maintained its low frequency sound, explains Marra.
But singing over traffic and other city noise isn't the only problem for birds. It turns out that big buildings distort bird songs as well. The sound bounces off the buildings, which absorb and refract bird songs.
So what does this all mean for the bird's prospects? At this point, it's unclear, says Marra. He says animals are adjusting their communication -- changing their accents and the way they speak -- but to what degree this change is affecting the survival of their species is still being studied.
Urban environments pose many challenges for animals, explains Marra, and researchers are just now starting to quantify those challenges. It's not just about where animals nest or eat; it's also about how well they can communicate in this urban jungle.
Urban Carolina Wren:
Rural Carolina Wren:
[Music: "Sing Sing Sing" by Incredible Bongo Band from Bongo Rock]