These highly social birds can make ‘sentences,’ just like humans

Tits amazing are birds Japanese. If you didn’t get that, you wouldn’t be alone: Humans figure out the meaning of sentences like this using grammatical rules such as word order. It turns out that Japanese tits, social birds that live in Japan and the Russian Far East, do it too. These wild birds respond to calls they’ve never heard before only if the chirps are in the right order, researchers report today in Current Biology.

When a predator threatens the flock, Japanese tits produce something called a “mobbing call,” with the sequence ABC-D. By itself, the ABC part of the call means “danger.” But the D part of the call—similar to the “recruitment call” of a close relative, the willow tit—attracts flock members when there’s something to share, such as food. When the two parts are produced together, Japanese tits flock together to mob the intruder.

To find out if the order of the calls mattered, researchers created a song that Japanese tits had never heard before—an artificial sequence made up of the Japanese tit’s ABC alert, followed by the willow tit’s recruitment call, tӓӓ. (You can listen to them, above.) They then played it from a loudspeaker for a flock of nearby tits.

When Japanese tits heard the ABC- tӓӓ call, they turned their heads, looking for a predator, as they approached the loudspeaker. But when the artificial sequence was reversed (tӓӓ-ABC), the birds didn’t react.

The fact that Japanese tits responded to artificial, mixed-species sequences suggests that they don’t perceive the ABC-D song as a unique message—“mob”—but rather as a message with two parts: “alert and approach.” That suggests, the scientists say, they get its meaning only if the sequence is in the correct order—just like humans.