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.
Menteng and the Boats
Like Danur, Menteng also hangs out near the river, but he is near the wider Joloi River that marks the eastern boundary of our release site and he doesn’t go in too deep. These males spent the best part of eight years on the islands receiving food that arrived by boat with our technicians, and waiting for food deliveries seems to be a hard habit to break! Despite this he is clearly able to find food for himself and he is in good condition, eating well and active.
We try and observe him every two weeks or so to check his health, but Menteng makes it difficult for us. He is developing into a fully mature male, with growing cheekpads and big body-size, and clearly full of testosterone which means he can sometimes be quite aggressive. He often comes down to the ground when we are near, following us and slowly chasing our observers back to the boat. We assume he simply wants to get food from us, and sometimes gets a bit frustrated if we don’t have it. Sometimes we need to jump into the river to get away! This is the difficult part of our work, as we have a responsibility to all our released orangutans to make sure they are well post-release, but of course need to keep safe ourselves.
Little Ebol is doing very well so far, she is moving and eating very well, the monitoring team were able to follow her on more than three occasions, just to be sure that she is in good condition and happy in the forest. She likes to eat a lot and make a nest and sleep from early in the evening, then the next day she is again very active and traveling to look for her food.
Markisa’s Special Family
This family is really special. Markisa is taking care of Uli and Mango is taking care of the entire family. Manggo and her sister Uli both look healthy and they really enjoy playing together. Mango is very protective, and if the monitoring team gets too close she will kiss squeak and breaks branches off the trees. Markisa on the other hand is very gentle, always taking care of baby Uli. They move together and like to travel very much. They love to be together and it is very special to see Uli when her sister Mango comes close, they touch each other, rest, eat and then travel again. We have a lovely photo of Markisa, very quiet letting little Uli sleep, it was a wonderful sight and really sweet.
We also have news of Gadis, Astrid, Emen and Isis, all of them healthy and doing very well. Adapting to the forest is not easy, but once they begin to explore, things get better.
And to finish… thanks to Orangutan Outreach for the new radio receivers for radio tracking. We are now getting a lot of signals… another report very soon!
Text by: Patricia Murcia V. and Ike Naya Silana