We thumb through real estate listings and drive around neighborhoods to find the best place to live, but some birds have it easier—they just listen to songs.
Male black-throated blue warblers sing to their newborn chicks in the autumn, probably trying to teach the young ones to sing themselves. But biologist Matthew Betts from Oregon State University, along with two Canadian colleagues, studied the warblers in New Hampshire and found that the song of males who successfully reproduced is also a cue—when other males hear it, they assume that location must be a good place to nest, and so they’ll try to return there the next year. Not only that, the scientists say, but eavesdropping on the songs other warblers can override the birds’ other senses.
To test how much the songs of other birds controlled the birds’ nesting patterns, Betts and his team recorded the male warblers’ song, then went to places that would make lousy bird habitat and played back the recording. Sure enough, Betts says, the next spring male warblers came back to these poor sites, despite the fact that a quick visual inspection would tell the birds that the habitats were bad places to live. All in all, he says, the birds were four times more likely to trust the song than their own eyes, and the poor females followed the males even into a bad situation.
For black-throated blue warblers, it seems successful reproduction depends on singing and spying on the songs of others to find the best nesting locations. But that’s a treacherous way to live: As the study points out, singing is a risk—making a bunch of noise alerts predators to your presence. And when you trust your ears, it’s easy to be led astray—at least by curious biologists.
Image: U.S. Forest Service/Wikimedia Commons