If you approach a door at the same time as someone else, the other person may make it clear with a hand gesture that you can go in first. That’s quite common for us humans. But scientists have now discovered that some birds do that too.
This can be read in the magazine Current Biology. “Our latest discovery is that Japanese great tits use gestures to communicate with their partners,” researcher Toshitaka Suzuki summarizes the study succinctly.
Surprising
It is a surprising discovery. It was long thought that communication through gestures was something that only humans do. We now know better; observations of great apes later showed that they also engage in this form of nonverbal communication. And follow-up studies even showed that other animal species – such as ravens and fish – could also sign. But often these involved ‘simple gestures’, which were aimed, for example, at pointing others to an object or something else interesting. However, symbolic gestures – such as a small movement with an open hand to indicate that the other person can enter somewhere before you – seemed to be used only by humans. And researchers also thought they could explain; such gestures appear to require complex cognitive skills.
Observations
But now researchers have shown that the small Japanese great tit (Parus minor) is capable of symbolic gestures. They base this conclusion on observations of 16 Japanese great tits, which together formed 8 couples. These couples devotedly care for their young, which were in a nesting box. And the researchers observed the Japanese great tits as they approached that nest box with food hundreds of times. And soon she noticed something. When the parents brought food to the nest box, they often first settled near the nest box, after which one of them flapped its wings a bit. And promptly the other went into the nest box first, while the bird that had moved its wings waited its turn. After observing hundreds of these visits to the nest box, it is clear to the researchers: by flapping its wings, the bird signals that its partner can enter the nest box first.
Surprised
“We were surprised that the results were so clear,” Suzuki said. “We saw that the Japanese great tits only flap their wings in the presence of their partner and after we saw that, that partner almost always entered the nest box first.”
Females gesture more often
The research reveals that females ‘gesture’ more often than males that their partner can go first. It did not matter which of the two arrived first in the vicinity of the nest box. And when females flapped their wings, it was often the male who entered the nest box first. When the female was not flapping, she usually entered the nest box before the male.
A rather convincing gesture
According to the researchers, the fact that we are really dealing with a symbolic gesture and not just some random fluttering is evident from various factors. So they first point out that the birds only make ‘the gesture’ when their partner is present. And that partner almost always responded by entering the nest box first. Furthermore, the fluttering stopped as soon as that partner entered the nest box. In addition, the researchers reveal that the fluttering was clearly directed at the partner and not at the nest box; a strong indication that we are not dealing with a ‘simple gesture’ that is only aimed at pointing out the location of the nest box to the partner.
“There is a hypothesis that walking on two legs allowed humans to move their hands more freely, which in turn contributed to the evolution of gestures,” Suzuki explains. “Similarly, when birds perch on branches, their wings can move more freely and we think that facilitates the development of gestural communication. We will continue to decipher what birds are trying to say with their gestures, sounds and combinations thereof. This not only allows us to further explore the rich world of animal languages, but is also important if we want to unravel the origins and evolution of our own language.”
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