Batikap has very hot days. On one of those days, Joy and Owang from our monitoring team arrived at camp with strange news about Danur. Even they could not really believe it, and they knew that nobody else would, so they brought us a video… of Danur swimming! When they told us, we really didn’t believe them, we thought it was a just a joke, but then they showed us the video. And yes, we really do have a swimmer in our orangutan group! At first, Danur went very close to the water a couple of times looking as though he was thinking about going in, but nothing happened. The day got hotter and eventually he could not resist and in he went for a lovely swim!
No-one has ever seen wild orangutans swimming – they stay out of the water because of the risk of crocodile attack and because they are not adapted for swimming – they sink very easily. Thus it was a great surprise when orangutans on the islands at Nyaru Menteng started entering the river and experimenting with different swimming techniques. At first they waded in to try to retrieve food that had fallen from the feeding platforms into the water, and in so-doing they slowly got used to being in the water. Some of them started wading up to their neck, others realised they could use floating logs to support their weight and take them into deeper water. Eventually some of them started copying fishermen and tried to catch fish – and were successful on many occasions! These behaviours spread through the population by social learning until many of the males and some of the females became confident in the water. Now that they have been released, it is perhaps unsurprising that these behaviours remain.
The river in Batikap is much faster-flowing than at Nyaru Menteng, and can rise and fall rapidly after rains, so the orangutans need to be more careful here. Danur is confident in the water, but it appears he is keeping to areas where he can touch the bottom with his feet. He remains deep in the forest, paddling and swimming in the shallow Posu River upstream from our camp. He appears to be crossing the river by wading and then launching himself with a jump and a few paddle strokes across a narrow stretches of deep water. Despite this, ‘true’ swimming is still not known in orangutans. He wouldn’t be able to cross the deeper, wider rivers that lie downstream.
Text and Photos courtesy of BOS Foundation