LONDON (Reuters) - European starlings are not just exceptional songbirds and mimics they also recognize a grammar in their songs in a way that was thought to be unique to humans.
Scientists in the United States have discovered that the birds can be taught to identify different patterns of organizing sounds used to communicate.
"We show that European starlings accurately recognize acoustic patterns defined by a recursive, self-embedding, context-free grammar," said Timothy Gentner of the University of California San Diego (UCSD), in the journal Nature.
Recursive grammar, in which words and clauses are inserted into sentences to create new meaning, is found in all human languages. It was considered a type of linguistic boundary that separated humans from other creatures.
"Now we find that we have been joined on this side of the boundary by the starling. It should no longer be considered an insult to be called a bird-brain," said Daniel Margoliash of the University of Chicago, a co-author of the study.
While humans change a sentence from "the bird sang" to "the bird the cat chased sang" by inserting words, starlings combine chirps, warbles, trills, whistles and rattling sounds.
The scientists discovered their ability by recording eight different starling sounds and combining them to make 16 artificial songs, some more complex than others, which had different grammars or patterning rules.
After teaching the birds to recognize the different sets of songs, nine out of 11 birds could distinguish the patterns and grammatical rules.
"These birds are a lot smarter than you might think," said Margoliash. "They have innate abilities. They solve interesting problems and learn difficult tasks."