Living a town away is the same as being stuck decades in the past, at least according to white-crowned sparrows. Researchers played four recordings to a group of male birds in Tioga Pass, California: current songs from local white-crowned males, 30-year-old songs from local males, current songs from males that live about 50 km away, and current songs from males that live 600 km away. Current local songs elicited the most aggressive response—the males dive-bombed the speakers that played the tunes—while the birds were fairly unfazed by the far, far away songs. But the males had a very similar reaction to both the 30-year-old songs and the 50 km–away songs: They waved their wings and approached the speakers, but not as closely or fiercely. The findings, reported online tomorrow in Biology Letters, could give clues to which acoustic features—such as tempo and frequency—mark a song as threatening, and how those subtle changes affect mate competition and choice over time.
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