Scientists have shown that birds move with the times by updating their songs; play them an old one and, just like teenagers at a disco, they'll desert the dance floor. Elizabeth Derryberry, from Duke University North
Carolina, had been studying the process by which birds develop local "accents". Ecologists have suspected for some time that birds have regional dialects and pay more attention to their own dialect than a foreign one, but the rate at which these local languages evolve wasn't known. So Derryberry compared samples of male white-crowned sparrows' songs recorded in 1979 and 2003. The more contemporary song had a lower pitch and was also slower, but would the birds notice? To find out she then played the samples to male and female birds. Just like the Birdie song at a wedding, the older material went down like a lead zeppelin with the listening birds, who much preferred the more recent songs. Upon hearing the contemporary material the females solicited more copulations, and the males strutted about oozing territorial aggression. These results show that, within a relatively short time, meaningful differences in song styles can emerge, and this could have the effect of creating a barrier to mating between isolated populations. Derryberry, who has written up the research in the journal Evolution, suggests that this could be one of the ways in which new songbird species emerge.