This last month has been extremely stressful for all of us at Sikundur research station in North Sumatra while we’ve been following two of our favorite orangutans, Suci and her 3-year-old infant Siboy. As I mentioned in a previous blog, while I was in Medan for a break the boys sent me a text saying Suci had some injuries on her back, which I assumed she’d received from Brutus, an unflanged male who was following her around trying to engage in copulations the last time we followed them. However, once I got back to camp, it became apparent an orangutan probably didn’t inflict the injuries. It’s more likely they came from air-rifle pellets and they were causing Suci serious discomfort, which was having a knock-on effect on Siboy’s quality of life too.

On my first day back, we headed out at 5:30 a.m. to Suci’s night nest, in the center of the grid, not too far from camp. I knew from the previous day’s data that Brutus was still following the pair, along with an adolescent male, Kundur, so I expected it would be a fairly lively and interesting day. However, while the two males were up and active at 6 a.m. on the dot, Suci stayed in her nest until nearly 9 a.m., which although not unheard of, is generally a sign that the orangutan isn’t feeling well. The reason we all like Suci and Siboy so much is that they’re very well habituated, often coming close to us observers, giving us lots to see and record from their behavior. This also meant that once she finally woke up, I very quickly got a good look at the injuries, which were terrible!

As you can see from the photo above, Suci had around 10 large, open wounds on her back (they would split apart and join together during the time we followed, making an accurate count difficult), which seemed to be causing her serious problems as she barely moved at all on that first morning, instead eating for a little while before making another nest at 11 a.m. While she slept, we tried to come up with potential plans for dealing with the situation, while simultaneously sending photos back to the Sumatran Orangutan Conservation Programme’s (SOCP) office using our phones in order to get the quarantine vet’s opinion.

As we came up with ever-more outlandish plans for treating the wounds, it became apparent that as much as we wanted to help, there isn’t really much that we can do for a wild orangutan in a national park. If this was a rehabilitant animal at SOCP’s sites in Jambi or Jantho we could have intervened, either by feeding Suci medication hidden within in fruit or in an extreme scenario, tranquilizing her and bringing her into captivity until she was fully recovered. Instead, we’d just have to keep following her and hope she got better.

What made matters worse for us was watching Siboy struggle. He’s still breastfeeding and usually Suci will carry him around. However, given her injuries were on her back where an orangutan would usually carry its infant, Siboy would now have to travel unassisted at a very young age. When Suci began to travel, Siboy would quickly get left behind, causing him to change from a fun and extremely playful infant orangutan into a completely different animal, alternating between screaming for his mother to wait and appearing listless when the pair stopped to eat or make another nest.

The first few days I followed them were tough, both emotionally and from a work standpoint. Every day was just like the first. Suci would wake-up late, manage to travel only around 200 meters (as opposed the usual 600) and sleep for around half of her waking hours, a far higher proportion than normal. This left me with a difficult decision to make. This kind of outlying data from a clearly sick animal isn’t going to be useful for my thesis. Furthermore, I couldn’t very well start running playback experiments on an already stressed out and struggling individual. However, despite the pressure to get results intrinsic to a PhD project, I didn’t think there was any way I could have let her go. If she died, the only option available to us (provided the national park gives us permission) would be to capture Siboy, thus subjecting him to a life in captivity until he developed sufficient skills to function alone and could be released. It seemed like a morbid thought, but at least, I figured, in this worse case scenario, we would give Siboy a shot of living in the wild, rather than perishing with his mother.

What also helped (for my mental state at least!) was the office’s opinion that although the air-rifle pellet wounds looked horrible, they’d seen animals brought into quarantine with far worse injuries, and these animals had made a full recovery. They told us to keep following for as long as possible, and hopefully Suci’s condition would improve.

Fortunately, as we followed her for a two-week period (a big effort, thanks so much to all involved!), Suci’s condition slowly began to improve. The wounds, although they still looked nasty, began to take on more color as blood flow returned, and she gradually began eating and travelling more while reducing her resting periods to a more normal level.

She was still waking up late, however, and while this could be attributed to the injuries, I think it probably had more to do more with the pair’s constant companion, Brutus, and his amorous desires. Every morning, he would wake up early and head straight to Suci’s nest where he would stare at her for a while before going off and feeding, repeating the process a number of times until Suci got up. I don’t think she was happy to have him around, since having an extra orangutan in the group is severely taxing on an individual, requiring extra travel and feeding time, especially in an area like Sikundur where food is limited and widely dispersed. Thus, spending more time resting might have been a tactic to mitigate these stresses and, I think, also served to frustrate Brutus in the hope he’d leave her alone.

Interestingly, although forced copulations are common with unflanged male orangutans, Suci would periodically allow Brutus to copulate, although she was entirely passive in these encounters, simply lying back in the tree, rather than proceptively encouraging their mating or actively resisting. I think perhaps this is because Suci can’t have an infant at the moment, given Siboy’s young age, so there wouldn’t be any benefit for her in resisting the larger Brutus, especially while she’s recovering. It’s interesting to note that prior to her injury she rarely copulated with him, perhaps indicating her movement provided a form of resistance not possible while injured. Siboy, however, was not so passive, screaming and hitting Brutus as he tried to copulate. Brutus seemed unperturbed, giving Siboy the occasional whack, but generally just staying out of range.

It must be difficult for Suci, having this ever present shadow in the canopy, whom she can’t outrun, so I’m hoping that Brutus will soon leave the pair alone, since it must also be a struggle for him to be so limited in his own ranging movements. For now, however, we’ve had to stop following them (we ran out of staff due to the Eid al-Fitr holiday). I’m pleased that Suci seems much better, but also really sad that someone appears to have come into the national park and shot her with an air rifle, perhaps for hunting or just for fun.

Such shootings are one of the major issues at a site like ours, which is so close to large amounts of human habitation, meaning the forest suffers a massive amount of anthropogenic destruction and encroachment primarily from illegal logging, agriculture and poaching. Sadly, however, this also makes it one of the most vital sites to study, and incidents like this will become more common since this is the direction towards which the amazing Gunung Leuser ecosystem is heading as the population of Sumatra continues to grow (currently around 52 million) and the Indonesian government continues to aggressively develop the island with roads and oil palm plantations.