I am inherently skeptical of news about linguistic features in the sounds emitted by animals and birds, as I am about the ability of animals and birds to wield human language (see, e.g., this 2004 post), but “Experimental evidence for compositional syntax in bird calls,” by Toshitaka N. Suzuki, David Wheatcroft, and Michael Griesser, looks intriguing; here’s the abstract:
Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax). Although animal vocalizations may be comprised of different basic elements (notes), it remains unknown whether compositional syntax has also evolved in animals. Here we report the first experimental evidence for compositional syntax in a wild animal species, the Japanese great tit (Parus minor). Tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. 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. However, receivers rarely scan and approach when note ordering is artificially reversed (‘D–ABC’). Thus, compositional syntax is not unique to human language but may have evolved independently in animals as one of the basic mechanisms of information transmission.
It’s discussed in this Washington Post story by Rachel Feltman, which has a brief video clip and some backstory:
“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. […]
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 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.
Addendum. I’m not going to make a separate post of this, but it fits nicely here: Cat phonetics.