Written by Jack Poole (BNF’s Intern)
September 28th 2017
It was early.
The clouds were low as if a coastal mist had settled in above our heads. It felt pleasantly cool and needless to say, it felt mystic, particularly serene in camp and the surrounding rainforest this morning. I greeted Adul (a master of many trades) at 4.40am and we set off to the listening post ready to find and do some habituation of Group A.
The listening post was 200 meters down the railway. We got there at 4.50am and proceeded to wait for the song of the male of group A to begin. We waited patiently as we watched and heard the forest wake up, the clouds began to lift as the sun’s rays’ past through the different forest layers.
It continued to be so peaceful and still, until, a male gibbon coda (the male song) could be heard from the listening post in the direction of Camp. Adul and I backtracked, slowly and carefully walked down the rail back to camp until the gibbon was in both ear and eyeshot. He was alone, but oddly it was not the adult male of group A, known to researchers as Air, but a younger subadult male. We sat listening and watching him about 20 meters way from him, we were on the rail and he was sat in a Terontang tree feeding and singing. The feeding and singing simultaneously weren’t going too well for him as he kept choking and coughing, which is possibly the most audibly cute noise I’ve been heard in the forest.
He was singing for about 40 minutes then began to move out of our view, we decided to relocate ourselves to transect 0, and there we found him moving in the general north direction away from us.
He was very fast and went far ahead of us. Though we weren’t worried about losing him as we could see rustling in the distance about 50 meters ahead. We scrambled through the trees over to the rustling and it transpired it was actually the Camp group of Red Langur monkeys who were feeding, directly above us. Adul and I sighed in deep Air that we had lost the gibbon at 5.50am just over 40mins since the habituation had begun.
This was frustrating because habituated gibbons allow us to follow them as they do not flee so we can take behavioural data. The more gibbons we have habituated the larger the sample size of gibbons, which in turn potentially exposes more and different behaviours that vary between individuals.
As we were about to head back to our beds, the adult male, Air, began hooting. We followed the sound and caught up to three gibbons, just before the transect intersection between AA and secret west.
The smallest of three gibbons immediately fled away from us, the subadult who we had lost and now found retreated within sight but Air seemed perfectly content with our presence. The two of the three gibbons were confirmed by Adul to be male, the other was a possible juvenile male. Not having an adult female is rather odd for a group of gibbons. Gibbon groups are normally made up of two adults a male and female and then 1-2 offspring. Our trio here can be part explained by occurrences in February where the social dynamics of group A and group C changed. The theory being that Captain, the adult male of group C, stole Comel (a female) from Group A, whilst “gibbon divorcing” his former mate Coklat.
We followed the three gibbons as part of the habituation process, stopping when they stopped moving when they moved and Adul worked really hard trying to get photos of the three gibbon’s faces.
The trio near to transect BB shot off very fast and high-pitched calls could be heard. Adul and I decided to hurry and catch up to the action as an interaction was occurring. We caught up with the three gibbons of group A but also Group C’s Captain and Chilli. Captain, a strong and muscular male who dwarfed Air in bulk. The subadult, is slightly smaller than Chilli in size, but this didn’t stop him from chasing her away, only to get chased back by Captain, then for Air to intervene and both of them then chase Captain back. One on one Captain would have easily beaten or even killed Air or rival males. Though today he and Chilli, known for her precocious personality, were very much on the defensive.
Adul suggested that it was a boundary dispute and asked me what Comel looked like as he hadn’t ever seen her before, we could hear her in the background great calling. To us it seemed like it was a stalemate. The 5 gibbons, were all directly above our heads, within 20 meters, none except the youngest gibbon of group A were bothered by our presence much.
Group C are well habituated and very familiar with researchers, even using us to their advantage in the turf war, perching in branches above our heads to say, “we’re not scared”. The subadult male whilst earlier wasn’t fond off our presence and ran seemed to be more concerned with the presence of group C than us. He was very vocal, squeaking and calling and jumping up and down in the branches above.
After about 20 minutes of chasing each other group C were to our right and group A to our left. Suddenly, the subadult male leapt across the canopy and body slammed into a Chilli, knocking her out of the tree, and she tumbled, in what felt like slow motion taking the male down with her to the ground.
Both of our hearts winced, for little Chilli, (she she’s since been observed and is fine), hoping she was ok. This aggressive action, encouraged Captain to charge at the group A male to protect his little girl. Captain chased the male away only for all three males to chase both him and Chilli over canal A, followed by moments later, Captain and Chilli chasing the three males back over the canal again. Leaving group C on one side and group A on the other.
Comel had finally been spotted by us and Adul noticed something peculiar. He then gave me the choice of continuing of habituating group A or investigating why Comel was holding back and Captain and Chilli had been so defensive.
As group A brachiated eastwards, Adul and I traversed a makeshift canal crossing and caught up to Comel.
Then, ventrally clinging on to her was this barely week-old gibbon infant. Adul and I had found the new group C arrival for the first time!
I feel that this is possibly the best way to end my 4 months in Borneo, discovering and naming an infant gibbon. I hope Cosmo (what I have dubbed baby group C as) grows up to be just as mischievous and precocious as their big sister and has an excellently long and illustrious life, despite me not being here to witness it first-hand.