Urban environment may change a bird's song

(CBS News) The warm weather is luring migrating birds back north earlier than expected. Those birds will sing to find a mate. But it turns out for some, the language of love is changing.

CBS News correspondent Bill Plante reports that the migration is a March Madness of a different kind as countless birds start their seasonal journal and look for a mate.

But for a bird singing out to find a partner in the noisy urban jungle, it's tough. Even the echoes among tall buildings can confuse the bird's hearing.

Conservation scientist Peter Marra has discovered that urban surroundings actually changes how birds call out.

"Just like you, when you're in a bar, or if you're out in the street and there's a siren that goes by, you've got to shout, or you have to change your own voice so someone else can hear you," Marra said.

Working with researchers at the Smithsonian, Marre found that increased noise alters the pitch of an urban bird compared to that of its country cousin.

The range of the urban bird is more narrow, and the pitch of its song has gone up. That heightened pitch has scientists wondering: Will city birds be able to find love if their country cousins refuse to mate because they don't recognize calls from the urban hood?

For noted birder Harrison Glasgow, it comes down to the adaptability of nature.

"Nature simply wants a balance, and the birds that live in the city have to achieve that balance," Glasgow said.

Marra says more research is in the works to determine whether urban birds have simply adapted to the stress of city living, and what happens when Mother Nature passes down a different "tune" to future generations.