BY ZOE ELIZABETH BUCK ● MCCLATCHY NEWSPAPERS ● July 31, 2008
RALEIGH, N.C. -- Humans aren't the only creatures whose regional drawls and twangs give them away. The same thing goes for the songbirds, according to a study at Duke University.
"If you drive around the U.S., you'll hear the same species of songbirds," said neurobiologist Richard Mooney, who has developed a unique way to study how birds learn and published his results this year in the journal Nature.
"But if you listen closely, the songs sung by a swamp sparrow from a population in New York sound different from a swamp sparrow in Pennsylvania. ... It could be likened to a dialect, or an accent."
These dialects stem from the way that birds learn to sing -- a process that is much like the way humans learn to talk.
For most animals, including nonhuman primates, communicative sounds develop naturally, without the need for tutors. Only select bird species, humans and perhaps some whales incorporate both nature and nurture into vocalizations.
The similarities between the learning processes are clear even on a microscopic level.
"Though there's a large evolutionary distance between birds and humans, many of the brain mechanisms in the learning process turn out to be remarkably similar," Mooney said.
These brain mechanisms include a phenomenon known as mirror neurons, which Mooney and his team documented in birds for the first time. Mirror neurons are a type of brain cell that fires either because the animal is performing a certain action, or because it is seeing another animal perform that same action.
Using tiny devices mounted on the sparrows' heads, Mooney and his team at Duke were able to describe mirror neurons that fired in the birds' brains when they sang their own song or when they heard another bird sing a very similar song. The findings are the first descriptions of mirror neurons in a species other than primates and the first to associate them with vocalizations rather than movement.
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