A Bird calls syntax, the set of rules for arranging words and phrases to impact meaning, and it’s a lot like the human language, according to The Christian Science Monitor.
Sometimes people use syntax to impart complex combinations of ideas. “Careful, it’s dangerous” is a phrase that has meaning, and so is “come toward me.” When those two phrases are combined, they have a different meaning than they do on their own: They’re directing the receiver to act in a different way than either phrase would independently.
Until now, only humans seemed to use syntax this way. But a study published Tuesday in Nature Communications suggests that the Japanese great tit — a bird closely related to the North American chickadee — uses grammatical rules like these in its calls.
With a bird calls syntax, language would be difficult to arrange. All language, human and otherwise, revolves around turning meaningless sounds into something more. It’s widely accepted that many non-human animals use what’s called referential communication — specific sounds mean specific things to the receiver. Beyond that, there are two kinds of syntax that make speech more complicated, but also more useful: phonological and compositional. Humans have both, and until this new study, non-human animals had only been shown to have the former.
Phonological syntax turns sounds that individually have no meaning into ones with meaning. Suffixes and prefixes are a good example in human language, and other animals use strings of different notes that are never used individually. The Campbell’s monkey adds an “oooh” sound to the end of its vocalizations to increase the intensity of the message, and this sound is never used on its own — so that’s another example. Another study found that some birds won’t respond to calls unless the notes involved are made in the right order.
“In the course of 10 years of field research, I noticed that the Japanese great tit has a wide variety of call types and uses many different calls in different contexts,” lead author Toshitaka Suzuki of the Graduate University for Advanced Studies said. In a previous study, Suzuki showed that the birds used these complex calls as “words” that conveyed different meanings. He wondered if they might also string those words together to form compound messages.
It turns out they do — and the order of the message might matter in the same way it does when humans speak to one another.
Suzuki and his colleagues found that a call referred to as the “ABC” Bird calls syntax — a string of notes used to signal other birds to scan for predators — was often followed by the “D” call, which told other birds to approach. When the ABC-D call is made, birds were seen to conduct both behaviors: They flew toward the speaker but scanned for predators first.
“The really critical part of the study came out of the review process,” co-author David Wheatcroft, a postdoctoral researcher at Uppsala University, said in a statement. When scientific studies are submitted for publication, uninvolved scientists in the same field have to screen the research and declare it sound. In this case, both reviewers asked how the study authors could be sure that the particular combination of ABC-D was imparting a specific, compound meaning.