We know that gorillas can communicate through gestures, sounds, and facial expressions, but so far, research has been largely confined to African gorillas, and the study of orangutans has been limited to a few studies of captive gorillas. But now a new study describes gesture-based communication between wild orangutans, especially between orangutan mothers and their young children in southwestern Borneo.
Scientists studied 16 species of orangutans in the peat bog forest in Sabango National Park, Borneo Island, Indonesia, which is managed by the University of Palangkaraya and covers an area of 500 square kilometres. The scientists captured 681 hours of video and recorded the exchange by hand.
In total, they identified 858 voice signals and 441 gestures. Among them, they identified the meaning of 11 voice signals and 21 gestures. Apparently, the orangutan uses gestures to get another orangutan to do something. Scientists have found that orangutans can request multiple targets with one gesture, as well as multiple gestures to request a target.
By measuring when gestures stop, the researchers can determine the various targets requested, including giving objects, climbing the signaller, leaving, resuming the game, and stopping activity. Interestingly, non-red-haired orangutans used a greater range of gestures than adult female orangutans.