Birds may surprise us if we underestimate them. A study of Japanese tits has investigated birds’communication showing that they can “speak in phrases”, an ability previously considered unique to humans.

“Language is one of humans’ most important defining characteristics,” explained Dr. Suzuki and his colleagues from Sweden and Switzerland.

“It allows us to generate innumerable expressions from a finite number of vocal elements and meanings, and underlies the evolution of other characteristic human behaviours, such as art and technology. The power of language lies in combining meaningless sounds into words that in turn are combined into phrases.”

Demonstrating skills unexpected from them, Japanese tits – closely related to the common British garden bird the great tit – seem to be able to emit a “scan the surroundings for danger” phrase, and then add a “come here” transmission at the end, to create complex message resulting as “come here and scan for danger”.

Dr David Wheatcroft, of Uppsala University, Sweden, one of the co-authors of the study, observe that this may be the first known example of wild animals untrained by humans using “compositional syntax”, where different sentences with individual meaning are combined to create a new, two calls with independent meaning are combined to create something with a new meaning.

“This has never been shown before,” said Dr Wheatcroft. “The evolution of syntax – combining different words to form more complex expressions – was so far considered to be unique to human language. This study demonstrates that syntax is not unique to human language, but also evolved independently in birds.”

According to the scientists, Japanese tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. However, the analysis of the birds’ communications shows that there are some accepted and recognised standards in the parts that need to be respected.

“Our experiments reveal that receivers extract different meanings from ‘ABC’ (scan for danger) and ‘D’ notes (approach the caller), and a compound meaning from ‘ABC-D’ combinations,” the researchers explain.

Failing in respecting such standards may jeopardise the effective meaning as “receivers rarely scan and approach when note ordering is artificially reversed (‘D-ABC’).”

“Now it’s been shown in a wide range of species including chickens – which use different vocalisations to distinguish between aerial and ground predators – and in Japanese tits, which have different calls for ‘crow’ and ‘snake’. There certainly is something unique about humans; but maybe the building blocks, the basis for our higher abstraction abilities, are present in other animals.”

Parrots, bonobos and dolphins had all been trained to respond to combined phrases, they said, but the wild Japanese great tits were the first to have been shown to “use these building blocks of language on their own.”

The findings were published in the journal Nature Communications. “Understanding why syntax has evolved in tits can give insights into its evolution in humans,” Dr. Wheatcroft said.

Written by: Pietro Paolo Frigenti

Journal Reference: Suzuki T.N., Wheatcroft, D., Griesser, M., (2016) Experimental evidence for compositional syntax in bird calls. Nat Commun 7:10986. .