Little bird uses a linguistic rule thought to be unique to humans

I can attest that my African Grey parrot uses human grammar rules – subject and predicate – consistently and with different words to convey his meaning. He seems to understand the difference between nouns and verbs and how to put them together. Rachel Feltman writes in the Washington Post:

A study published in Nature Communications suggests that a small bird known the Japanese great tit uses grammatical rules in its calls. Until now, only humans seemed to use syntax this way.

(…)

“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 told The Post. 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.

Video: A study published March 8 suggests the Japanese great tit uses syntax, the set of rules for arranging words and phrases to impart meaning. (Toshitaka Suzuki)

Suzuki and his colleagues found that a call referred to as the “ABC” call — 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, told The Post. 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.

“Maybe they just hear ABC and D in close proximity and do both behaviors,” Wheatcroft explained. “So we said OK, we’ll do another experiment. Toshitaka reversed the call, and he played D-ABC for the birds. And they didn’t respond, or at least not as strongly or consistently as they did to ABC-D.”

So instead of just combining calls and producing two behaviors, there seems to be some kind of rule to prompt the compound behavior: approaching, but staying on high alert for predators lurking nearby.

The researchers aren’t sure what the rule is based on. Perhaps, since the predator-related piece of the call is more important, the birds have created this “rule” over time. Maybe syntax developed because birds that didn’t warn of danger before asking for a buddy to come over were less likely to survive. And no one wants to blunder into a predator’s line of sight on the way to a friend’s place.

The next step is to find out which other birds use rules like these. The Japanese great tit has close relatives in Europe, and the North American chickadee is a close cousin as well. They all have similarly complex calls — the chickadee gets its name for a “dee” sound that serves the same purpose as the “D” discussed in the study — and it’s possible they all use syntax.

Even if the birds evolved this love of grammar way back in the days of a common ancestor, their specific rules could still be different.