Wild bird uses wing gestures to politely say, 'after you'

A team of researchers led by the University of Tokyo has uncovered a fascinating aspect of bird communication. The study reveals that the Japanese tit (Parus minor) utilizes wing gestures to communicate a polite “after you” to its mate. 

This discovery challenges the prevailing assumption that complex gestural communication, akin to the symbolic gestures observed in humans and great apes, was beyond the capacity of birds.

The findings mark a significant advancement in our understanding of non-verbal communication mechanisms in the animal kingdom, particularly among birds.

Gestures and communication 

Human communication heavily relies on gestures, such as giving a thumbs up, waving goodbye, or pointing to convey messages without the use of words. This mode of communication was once thought to be exclusively human until observations of great apes like chimpanzees and bonobos demonstrated their ability to use body movements to express themselves nonverbally. 

Further studies extended this understanding to other animals, including ravens and fish, which exhibited simple gestural behaviors like pointing to indicate objects or interests. 

Symbolic gesturing in a non-human species 

However, the concept of symbolic gesturing, which implies a higher level of cognitive processing – such as a human showing an open hand to signal “after you” – had not been definitively observed in non-human species until now.

“In our latest discovery, we revealed that the Japanese tit uses gestures to communicate with their mate,” said study lead author Toshitaka Suzuki, an assistant professor of animal communication at the University of Tokyo. 

“For over 17 years, I have been engaged in the study of these fascinating birds. They not only use specific calls to convey particular meanings, but also combine different calls into phrases using syntactic rules. These diverse vocalizations led me to initiate this research into their potential use of physical gestures.”

Unique form of gestural communication

Observations conducted during the breeding season provided valuable insights into the behavior of Japanese tits. These birds, which form mating pairs and construct their nests within tree cavities, displayed a unique form of gestural communication. 

The researchers focused on 16 parent birds across eight pairs, closely monitoring their interactions during nest visits. Notably, when arriving at the nest with food, the birds would often perch nearby, and one would flutter its wings toward the other, signaling for its mate to enter the nest first. 

This wing-fluttering gesture, primarily exhibited by females, effectively determined the order of nest entry, mirroring the human ‘after you’ gesture.

Distinctive wing gestures

“We were surprised to find that the results were much clearer than we had expected. We observed that Japanese tits flutter their wings exclusively in the presence of their mate, and upon witnessing this behavior, the mate almost always entered the nest box first,” Suzuki said. 

The researchers concluded that this behavior satisfies the criteria for a symbolic gesture, as it is aimed at the mate rather than the nest box, distinguishing it from deictic gestures that indicate the location of an object of interest.

Understanding the evolution of gestures

Suzuki also touched on the broader implications of their findings for understanding the evolution of gestures, drawing parallels between the freed wings of perching birds and the mobility of human hands due to upright posture and bipedalism. 

“There is a hypothesis that walking on two legs allowed humans to maintain an upright posture, freeing up their hands for greater mobility, which in turn contributed to the evolution of gestures. Similarly, when birds perch on branches, their wings become free, which we think may facilitate the development of gestural communication,” he explained.

Communication and cognition across species

As scientists continue to unravel the complexities of avian communication, their work not only sheds light on the rich tapestry of animal languages but also offers key insights into the origins and evolution of language itself. 

This research underscores the importance of expanding our perspective on communication and cognition across species, bridging the gap between human and animal non-verbal interactions.

The study is published in the journal Current Biology. A video of the ‘after you’ gesture in Japanese tits can be found here.

Video Credit: Suzuki and Sugita, 2024/ Current Biology

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