The study challenges the belief that only humans are able to use grammatical rules to process strings of sound such as sentences.
The experiments, described in Nature Neuroscience this week, were carried out on Bengalese finches by Kentaro Abe and Dai Watanabe of the University of Kyoto in Japan.
Bengalese finches are tiny birds, which are easily domesticated and very social. They also do a lot of vocalizing. Each male has his own song call, which he varies quite a bit, but is distinctively his own, explains Abe. When he hears another male, his response is usually to make a burst of calls in reply (about 30 calls in 10 seconds).
Bird song can be thought of as being like a sentence, with the different sounds being like words. The scientists played jumbled-up bird songs to individual finches to see whether the birds responded with the usual burst of calls to the jumbled songs.
To their surprise they found that there were some jumbled songs that elicited a call-burst response and some that did not. Even more surprising: all the birds responded in the same way. If one bird ignored a jumbled call, all the other birds ignored that call too.
It seems that the order of syllables matters to the birds, and that suggests grammar in action.
"It's as if you were presented with a sentence like 'we will go to the zoo tomorrow,'" said Gisela Kaplan, an authority on bird song at the University of New England.
"Some versions of the sentence such as 'tomorrow we will go to the zoo' and 'we will go to the zoo tomorrow' are grammatically acceptable, others like 'zoo go we will tomorrow the to' are not."
"Obviously with these birds the syllables can't just be put anywhere, and that suggests that humans aren't unique in being able to order sound logically. The fact that birds can do this, even if only at a simple level, is mind boggling," said Kaplan.
Read more at Discovery News
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