Gestures are ubiquitous in human communication, used to point out objects or convey information, a phenomenon also found in great apes. While much research has explored gesture signals among great apes, little attention has been paid to other animal groups, leaving it unclear whether non-primate animals can employ symbolic gestures.
Toshitaka Suzuki, Associate Professor of Animal Linguistics at the University of Tokyo, has, for the first time, demonstrated through research that birds can utilize wing movements to convey specific meanings. This study was published on March 25th in Current Biology.
A female Japanese tit is flapping its wings. Image source: Toshitaka Suzuki
To gain further insights into this behavior among birds, Suzuki and his colleagues spent several years installing hundreds of nest boxes in a forest where Japanese tits thrive.
To mimic the natural tree holes where tits typically reside, each nest box featured a 7.5-centimeter-wide hole, just wide enough for a single bird to enter.
During the breeding season, the research team observed 321 nest visits by 8 pairs of tits, often seen carrying food to feed their chicks.
When a tit couple arrived together at the nest, each bird would perch on nearby branches before entering. About 40% of the time, the female tit would flap her wings briefly, facing the male tit. Subsequently, the male tit would enter the nest first, followed by the female.
However, when neither bird flapped their wings (which occurred in 44% of nest visits), the female tit typically entered the nest first. Researchers only observed one instance where the male tit repeatedly flapped its wings, prompting the female to enter the nest first. When the birds arrived separately, researchers observed no wing-flapping behavior.
Suzuki remarked, "We can conclude that Japanese tits use wing flapping to signal their mate to enter the nest first. This wing flapping serves as a symbolic gesture conveying the specific message of 'you first,' indicating to the other bird to enter the nest ahead. This study provides the first evidence that birds can utilize wing movements to convey specific meanings."
The findings suggest that communication among Japanese tits and other bird species is far more complex than previously thought.
"There's a hypothesis suggesting that language evolved from gesture communication. Therefore, this study can help us understand the evolution of complex communication, including the evolution of language," Suzuki noted.
Related paper information: https://doi.org/10.1016/j.cub.2024.01.030
