The researchers followed how the monkeys used the tunnel for several months. They found that the sakis used the sound system regularly throughout the study and, after the first few days, also began to sleep, groom, and socialize with other monkeys inside the sound device.
Kirsi Pynnönen-Oudman, research coordinator at Korkeasaari Zoo, says that food is often used to enrich the lives of animals in zoos. However, non-food stimuli must also be provided, especially for small animals that are prone to gain weight. ‘Sounds are really important to many animals in their communication with each other. The rainforest is full of different sounds and little monkeys are supposed to be sensitive to different sounds.’
‘The way of the future to stimulate the life of zoo animals’
The fact that animals are so interested in sounds is also reflected in the results of the study. The sakis were allowed to choose how much either calm music, fast-paced electronic music, sounds of rain, silence, or traffic noises they prefer to listen. The sakis preferred the sounds of traffic over all other sounds.
Ilyena Hirskyj-Douglas, postdoctoral researcher at Aalto University, says that the result was both unexpected and expected. ‘I've been working with animals for a long time and learned to keep an open mind. However, given that the sound of traffic is so unfamiliar to the sakis and not related to their normal daily life -- unlike, for example, the sound of rain -- it came as a surprise that they were interested in those sounds.’
According to Dr. Hirskyj-Douglas, the result suggests that scientists need to think carefully about what technologies work for animals, keeping an open mind and leaving the human perception at the door.
In addition to influencing what sounds they want to listen to, the white-faced sakis were able to influence the final form of the device. The researchers initially tested two prototypes and built the final sound device from the option that the monkeys used significantly more.
The tunnel-like box with a plywood floor and a transparent acrylic roof was the sakis’ favourite. Both materials were already familiar to white-faced sakis, and thanks to the shape and materials of the box, the tunnel acoustics were good without having to completely close the space. The shape and material were suitable for their habitat and to support the species-specific behaviour of the animals.
Dr. Pynnönen-Oudman from Korkeasaari Zoo says that sound stimuli have been used in zoos to some extent, but so far quite little has been tailored to particular species. ‘This could very well be the way of the future to stimulate the life of zoo animals.’
Link to the research article: https://www.mdpi.com/2076-2615/10/10/1768#
Postdoctoral researcher, Aalto University
Doctoral candidate, Aalto University
Research coordinator, Korkeasaari Zoo