The research group, led by Wouter Halfwerk of VU Amsterdam and Katharina Riebel of the Institute of Biology Leiden (IBL), developed and tested the RoboFinch in collaboration with the VU Amsterdam Technology Centre. “You can do things with a robot that the real-life creatures cannot do", says Wouter Halfwerk, associate professor at VU Amsterdam. “For instance, you can investigate whether birds pay attention to movement when they learn their language, just as human babies watch lips so they can learn to talk more easily.” The results of the initial tests with six different RoboFinches have been published in Methods in Ecology and Evolution under an open-source licence, so everyone can 3D print and construct their own robot.
“Just like children, young zebra finches start by babbling. They hear the songs of others of their species, remember them and start practising,” says Katharina Riebel. “Behavioural biologists want to find out more about this vocal learning, but up to now that has been done mainly by playing birdsong through a loudspeaker. But learning to sing involves a lot more, such as beak and throat movements, and posture. Zebra finches cannot learn as easily from a video recording as from another of their species.”
Making the robot finch began with a 3D scan and 3D printing an adult male at VU Amsterdam. Birds see colours differently from humans, so the team adapted the colours. As a result, the robot looked lifelike to zebra finches. Using high-speed cameras, the research group looked at the beak movement of a zebra finch, so as to make an exact copy. Rob Limburg of the Technology Centre knew that it would be a huge challenge because the beaks move very rapidly. “Nevertheless we succeeded, partly because we were able to use a specific component that we took from a toy model.” The bird moves well and for a number of songs the bill now moves entirely realistically. We had to do it frame by frame, 120 frames per second, so it was really laborious.”
Fortunately, the birds took to the RoboFinch as well. “Initially, zebra finches are generally wary of new objects, but they were enormously curious from the outset”, says PhD researcher Judith Varkevisser, who performed the experiments at Leiden University. “They come and sit on the perch alongside it and chirp to it. And even more importantly, the young birds sit quietly and study the RoboFinch when it begins to move and we play back birdsong. They genuinely seem to be listening to the robot! That proves that we can use the RoboFinch in our research into vocal learning and whether the movements associated with singing are important in that regard.”
DIY robot bird
With this positive result the Seeing Voices team can now compile a sort of kit made up of different aspects of birdsong. “Do we want movement only, audio only, or everything at the same time? We are also going to try to make the RoboFinch interactive. Then it can start singing as soon as the birds sit on a particular perch”, says Riebel. The scientific publication in Methods in Ecology and Evolution also provides files that enable people to make a robot themselves. “We are happy to share the blueprint with others in the hope that we be able to find out even more about vocal learning”, Wouter Halfwerk explains. “We really look forward to seeing what new insights we can obtain with this technique in the next few years.”