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.