A jolt of springtime hormones makes a female sparrow's brain more responsive to song, say researchers.
The female hormone estradiol doesn't do this by boosting the tissue's response to song, though. Instead, it dulls the reaction to junk noise, says Donna Maney of Emory University in Atlanta. Songs might thus stand out against a background of unromantic environmental sounds.
Scientists have learned that one of the ways hormones affect animals' behavior is by changing the ways in which their brains process smells and sounds.
Maney and her colleagues explored such hormonal tuning in captive female white-throated sparrows. The researchers gave half the birds tiny implants that released estradiol, which normally abounds in females during breeding season. The other half