Tiny Bird Is First Non-Primate to Make Symbolic Gesture

We humans think we know a lot. But when it comes to how animals communicate, we have a lot to learn, according to new research boasting the first known case of symbolic gesture in a non-primate. Many animals display body parts and some, including birds like magpies and ravens, make deictic gestures, like pointing, showing, and reaching. But only primates like humans, apes, and chimpanzees were previously known to communicate through more cognitively demanding symbolic gestures, like the little wave of the hand that signals to another "after you," per the study published Monday in Current Biology. That was until biologist Toshitaka Suzuki of the University of Tokyo began paying close attention to the behavior of pairs of Japanese tits.

Suzuki, who's been observing the small birds for more than 17 years, noticed when pairs arrived at their nest with food, one bird would often perch on a branch and flutter its wings. It would then enter the nest only after its mate. "This led me to investigate whether this behavior fulfills the criteria of gestures," Suzuki tells Science News. In observing pairs making hundreds of trips to nest boxes, he and colleague Norimasa Sugita of Tokyo's National Museum of Nature and Science discovered females nearly always entered the box first. But if a female fluttered her wings—and females did this far more often than males—the male would enter ahead of her. The researchers conclude the fluttering amounts to an "after you" gesture.

This "shows that Japanese tits not only use wing fluttering as a symbolic gesture, but also in a complex social context involving a sender, receiver, and a specific goal, much like how humans communicate," says Suzuki, who notes the birds were never observed fluttering when alone and the fluttering stopped only when its target entered the nest. "It's a really strong support to the notion that it's a symbolic gesture," Cornell University ornithologist Mike Webster, who wasn't involved with the study, tells Scientific American. "The bird that's the receiver knows what it means, and it does what it's supposed to do." The silent gesture may help the birds avoid predators, Suzuki notes. He and Sugita next aim to explore whether the birds combine complex vocalizations with symbolic gestures, as humans do. (More animals stories.)