Bird Brains: Great Tit Calls Use Syntax To Form Complex Sentences And Other Birds May, Too

Humans believe they are special, unique creatures in the animal kingdom with qualities that place us above our fellow, lesser beasts. But new research has revealed something very human about bird calls. Japanese great tits, and perhaps their North American cousin the chickadee, use syntax.

In other words, the humble little bird knows how to chirp in complete sentences, possessing a skill once thought to belong only to humans, Discovery reported.

“We now have good evidence that animal communication systems share many of the basic properties of human language,” said Toshitaka Suzuki, the study’s lead author. “For example, mammals and birds can use specific call types to denote specific objects, and Japanese great tits can combine different ‘words’ to send a compound message.”

To understand this research, it’s necessary to back up a little and explain what syntax is and how science believes animals communicate.

Syntax is the set of rules used for organizing individual words and phrases, which allows humans to communicate combinations of ideas, the Washington Post explained. Two separate phrases may have their own meaning when used on their own. But when combined together, they create an entirely different meaning.

Two kinds of syntax exist — phonological and compositional — and humans have both. Phonological syntax transforms meaningless sounds into ones with meaning. Suffixes and prefixes are a human example; the “oooh” sound a Campbell’s monkey adds at the end of its “words” to make them more urgent is another. Compositional syntax is the combination of individual and defined sounds to create a compound meaning.

Science once believed that animals only possessed phonological syntax — the new study shows that at least one little Japanese bird has both. Suzuki confirmed that at least one bird’s calls contain compositional syntax, combining chirps with specific meanings into complex sentences by trying to fool the great tit.

Suzuki already knew the bird had two alarm calls for their two main predators — jungle crows and Japanese rat snakes. He and colleagues David Wheatcroft and Michael Griesser studied the bird’s different note types, naming them A, B, C, and D. They already determined through different research that A, B, and C are chirped together to tell friends to “scan for danger.” The D note means “approach the caller.”

But the bird also chirps ABC-D together. When put in that order, the chirps have a compound meaning: “scan for danger and come here” (hence, compositional syntax). Suzuki played these bird calls, which were recorded and transmitted through a loudspeaker, to 21 adult great tits in the wild. Every bird listened to the calls’ command: they scanned the horizon for danger, then approached. Suzuki tried to fool the bird and changed the call to D-ABC. The birds didn’t respond at all.

The bird calls gain their use of syntax gradually over time. Baby birds only have a handful of chirps but copy their dad’s mating songs as they grow up. They may also learn how to tweet sentences from him, too. Researchers believe they’ve only uncovered one of many bird calls that contain syntax; great tits have a few other combinations of those notes, and researchers still don’t know what they mean.

“There is no evidence showing that non-human primates, even chimpanzees, use compositional syntax,” Suzuki said. “Combinations of sounds are very common in tits and chickadees, and are also found in other species of passerines (perching birds).”

Science has a lot more questions about how bird calls contain syntax. They want to know how great tits and its cousins evolved their complex language, and find out which other birds tweet in this way. It’s possible that all songbirds have this ability. As a cousin of the great tit, the North American chickadee (which gets its name from the “dee” sound that means “approach the caller”), may also use syntax.

Wheatcroft expects syntax isn’t just used in bird calls, but by all animals.

“We hope people start looking for it and find it everywhere. Because then we can start answering the question of how and why syntax evolved. For now, we don’t have any close relatives that we know who use syntax. And it’s a big question. Why not just convey a new meaning by creating a new word? Why does order matter? We hope that in the future, this research will help give us insight into why syntax evolved in humans.”

[Image via Eric Isselee/Shutterstock]