Long before the National Security Agency began eavesdropping on the phone calls of Americans, young song sparrows were listening to and learning the tunes sung by their neighbors.
University of Washington researchers exploring how male song sparrows (Melospiza melodia) acquire their song repertoires have found the first evidence that young birds choose many of their songs by eavesdropping on the tuneful interactions between other sparrows.
In laboratory experiments, the young sparrows were exposed to two adult "tutors," one of which they directly interacted with vocally and a second one that they only overheard singing with another young bird. Even though they learned from both tutors, the young birds acquired more than twice as many songs from the tutor on which they eavesdropped, said Michael Beecher, lead author of the study and a UW psychology and biology professor. Scientists study song learning in songbirds in part because it has a number of parallels with human language learning, and Beecher thinks eavesdropping also could play a role in how infants learn language.
Sparrows in the wild are thought to learn their songs in two phases. The first phase occurs in their first summer, when they hear and memorize songs sung by adult birds. The following spring, when the young birds are establishing their own territory, they modify and prune their repertoire so their songs are more similar to their neighbors. A song sparrows repertoire crystallizes at around 10 to 11 months of age and does not change.
Beecher and his colleagues earlier proposed that eavesdropping and interactive singing are critical in song learning. However, they could not determine if the young birds learned more by direct interaction with a tutor or by eavesdropping.
To answer that question, the researchers collected and raised eight baby sparrows for a two-part experiment. When they were about 15 days old, the birds were exposed to four adult sparrows for
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Contact: Joel Schwarz
joels@u.washington.edu
206-543-2580
University of Washington
29-May-2007