The meaning of "bird brain" might have to be re-evaluated after pigeons in a New Zealand-German study showed a surprising ability to distinguish between words and non-words through letter combinations.
The authors of the study involving Otago University and Ruhr University say the pigeons' performance was on par with that previously reported in baboons for this type of complex task.
The research, published in the international journal Proceedings of the National Academy of Sciences, is the first to identify a non-primate species as having "orthographic" abilities.
Four pigeons were trained to peck four-letter English words as they came up on a screen, or to peck a symbol when a four-letter non-word was displayed.
The researchers added words one by one and the pigeons built vocabularies ranging from 26 to 58 words, and more than 8000 non-words.
To check whether the birds were learning to distinguish words from non-words, rather than merely memorising them, the researchers introduced words the birds had not seen before.
The study's first author, Dr Damian Scarf, from Otago University's department of psychology, said the pigeons correctly identified the new words as words at a rate significantly above chance.
Professor Onur Gunturkun, from Ruhr University, said: "That pigeons - separated by 300 million years of evolution from humans and having vastly different brain architectures - show such a skill as orthographic processing is astonishing."
Professor Michael Colombo, from Otago, added: "We may have to seriously re-think the use of the term 'bird brain' as a put down."