Going Apes***: The Joys of Studying Gorillas in D.R. Congo

(a.k.a. 2 pigeons for a bar of soap, tropical diaper rash, and the healing powers of palm oil)

The man in front of me stood proudly gripping the legs of the African green pigeon (Treron calvus) he had recently captured. We had just arrived at our first stop on a 2-day trek out to a remote campsite in the lowland tropical forests of eastern Democratic Republic of Congo (DRC). Our plan was to track a group of wild Grauer’s gorillas (Gorilla beringei graueri) for a week. My particular research interests mean that I actually spend a lot of time studying gorilla dung. To many, this work might seem less than glorious…but, I love poop. Poop provides scientists with a wealth of knowledge about animals that we may never see. For my PhD dissertation, I am trying to understand how parasites are transmitted among wild gorilla social groups. These parasites include nematodes that live in the gut, so when the worms reproduce, their eggs end up in their gorilla host’s dung. That means I have to process a LOT of fecal samples. At one of my field sites, this entails carrying a mobile wet lab into the depths of a tropical African rainforest. We had just crossed the Loa river in a pirogue (French: dugout canoe), which required several trips because our equipment included, amongst other things, food for one week for a field team of about 15 people, a drone, a microscope, camping equipment, and of course, a giant bag of collection tubes.

Getting to our target campsite with all of our equipment involved multiple trips back and forth across the Loa river in a small dugout canoe.

After this crossing, we took a short break at a pigeon hunting camp. I had heard about the traditional pigeon hunting practices in the North Kivu province of DRC and was fascinated. The head pigeon hunter was eager to share his stories and had brought out a basket that contained a few green pigeons.

A pigeon hunter with his catch for the day. His family has lived in this small hunting camp in the middle of the tropical forest in D.R.C. for generations.

Capturing green pigeons is an involved process and the technique has been passed down for generations in his family. On this particular day, the pigeon hunter was wearing a Spiderman tank top. The irony was not lost on me that his livelihood depended on superhuman tree climbing skills to lay a sticky web (see pictures below). I peered at the basket of pigeons and a browning piece of paper nailed to a wooden stake at the center of this tiny hunting camp. Scribbled on the paper were the barter-and-trade values for x number of pigeons: a bar of soap could be bought for about 2 pigeons, while the value of two batteries was about 1 pigeon. This family could capture anywhere from 10-20 birds every day. That might not seem like much, but in an increasingly fragile and fragmented forest, imagine what multiple hunting camps could do to the pigeon population. In other tropical forests in Congo, these pigeons are even more at risk [1].

Traditional green pigeon hunting is an involved process: A sticky glue-like substance is made by boiling the sap from a couple of plant vine species. This glue is then applied to sticks attached to the exposed branches of tall trees surrounding marshes. The salty mud in this waterlogged habitat attracts green pigeons, who often roost on these trees. When the pigeons land on the sticky branches, they are unable to fly away in the morning. The pigeon hunters can scale up the trees and easily pick the birds off the branches.

Now, don’t get me wrong: although my research is largely motivated by conservation goals, I do support subsistence hunting (hunting for survival, providing food, or currency, for yourself and your family). I understand that conservation practices, more often than not, result in a cultural white-washing that may only temporarily protect a few charismatic species like gorillas. In the process, non-charismatic, understudied species as well as traditional hunting practices that have been around for centuries might be lost [2]. This isn’t a new phenomenon, but I became acutely aware of the issue that day. The sad reality is that gorillas are far more interesting and appealing to the public. However, it is possible to protect other animals by protecting species like gorillas.

Gorillas and other great apes are charismatic and can serve as flagship species for conservation efforts for entire ecosystems, including many of the lesser known species within it, including the green pigeon.

My initial plan was to collect dung from the night nest site of only one gorilla group. By some stroke of luck, another gorilla group happened to be close enough that we could get to their nest site the following morning. As a rule of thumb, if scientists can get more samples, we do. The predictive power of our hypotheses increases if we have a larger sample size. So, for the sake of science, we hiked an extra eight hours so that I could get more gorilla poop. I was on cloud nine as I tucked away over 20 gorilla samples in test tubes, blissfully ignoring the torrential downpour that had blessed our little mission. Unfortunately, my thighs had not been so blissfully unaware. Laden with our quarry, we began our hike to the final campsite, just as a searing pain shot down my legs. After hiking around with a heavy backpack for nearly 12 hours and squatting in the pouring rain to collect samples, half my upper legs had erupted in what can only be described as an insane diaper rash. I was quite embarrassed to admit to my PhD advisor that walking two steps forward was nearly impossible and that I absolutely HAD to change into a pair of dry pants. To my surprise, he told me quite honestly that the other trackers also often suffered from this affliction. Their solution: lathering the sore spots with unfiltered palm oil, a thick, viscous fluid that is a vivid orange color.

In Central Africa, unfiltered palm oil is used ubiquitously for cooking purposes. However, this summer, I learned about an unconventional use for the thick, orange substance: as a salve to treat diaper rash. [Source]

So, I did what many a self-respecting scientist in the wild has done: I hid behind a tree and dropped my pants. I will always remember the sound I heard as I was bandaging up my burning, orange thighs. The tropical bird songs, cicada-like chirping and hushed, sympathetic whispers of my field team were replaced by a cacophony of siren-like screams. Chimpanzees! They were so close, we could hear the direction in which they were traveling: undoubtedly, away from us. Here I was, surrounded by the calls of a truly wild chimpanzee community, covered in orange goop with my pants pulled down to my knees. I relished the moment, quickly zipped up my pants, and we recommenced our journey with the sounds of chimps retreating into the depths of the lush, green Congolese forest.

Part of the perks of hiking through primary tropical forest in the Congo Basin include discovering new miniature waterfalls along the way.

When we finally arrived at our campsite, happy with the first gorilla fecal samples of the field season, we were exhausted. But my work wasn’t over: since I had collected fecal samples that day, I would need to process them immediately the next morning, so it was vital to prepare my temporary lab station. The field team has setup and dismantled temporary campsites in the forest countless times, and within minutes a large blue tarp was erected and tied down to short, stout saplings. I quickly set up my test tube racks, microscope, weighing scale, water filtration system, and wash buckets. When I went to bed that night, I reapplied the orange palm oil, somewhat skeptical that this loudly-colored ointment was going to do any good. I needed to be on top of my game for the next few days of sample processing and hiking to collect additional fecal samples. I fell asleep, doubtful, but happy with the unforeseen success of our first day in the field.

My mobile forest laboratory was cramped: I had to set up a water filtration system, microscope, weighing scale, and wash bin to process gorilla fecal samples and count parasite eggs in the field.  Check out my temporary test tube drying rack tree stump (center image). [Photo credit (right image): Dr. Damien Caillaud]

At the end of the trip, I had over 50 gorilla fecal samples from three different social groups. It might not seem like much, but even this is the most extensive sampling conducted on lowland Grauer’s gorillas. Difficulty accessing the remote forests in which the gorillas, green pigeons, and chimpanzees live means that little to no research has been done on these animals. Protecting these threatened, remote ecosystems requires a collaborative effort between researchers, conservation NGOs, government authorities and most importantly the local families that have lived and hunted in these forests for decades. The issues facing Grauer’s gorillas cannot be taken lightly. This critically-endangered subspecies has declined by nearly 80% in the last twenty years due to deforestation and hunting pressures [3]. While the green pigeon is currently listed under the category “Least Concern” according to the International Union for Conservation of Nature (IUCN) [4], there are no recent studies that have evaluated their current population size, so it is likely they are more endangered than we know. It is only with successful funding strategies, responsible policy-decisions, open communication, and trust between all partners that their precarious plight can be reversed. I am happy to report on the efficacy and restorative powers of palm oil on angry skin rashes. The morning after that fateful first field day, my diaper rash had all but disappeared. If only all our other problems could be solved with a handful of orange goop…

Neetha Iyer is a graduate student in her third year in the Department of Anthropology at UC Davis. Her research interests include disease dynamics and the evolution of sociality. She will eagerly talk to you about primates, poop, and parasites, so hold onto your lunch. She thanks Dr. Anna Goldfield for the puntastic “Going Apes***” alternative dissertation title. Her dissertation work is made possible by collaborations between the Dian Fossey Gorilla Fund International, l’Intitut Congolais pour la Conservation de la Nature, and the local community living in Nkuba village in eastern D.R. Congo.

All images, unless otherwise noted, were taken by Neetha Iyer


  1. National Geographic “Will the Congo’s Green Pigeons Go the Way of the Passenger Pigeon?” by Steve Boyes (August 29, 2012). URL: https://blog.nationalgeographic.org/2012/08/29/will-the-congos-green-pigeons-go-the-way-of-the-passenger-pigeon/
  2. Dowie, M. (2011). Conservation refugees: the hundred-year conflict between global conservation and native peoples. mit Press.
  3. Plumptre, A. J., Nixon, S., Kujirakwinja, D. K., Vieilledent, G., Critchlow, R., Williamson, E. A., … & Hall, J. S. (2016). Catastrophic decline of world’s largest primate: 80% loss of Grauer’s Gorilla (Gorilla beringei graueri) population justifies critically endangered status. PloS one, 11(10), e0162697.
  4. BirdLife International. (2016). Treron calvus. The IUCN Red List of Threatened Species 2016: e.T45433492A95154637. http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T45433492A95154637.en. (this link does not work)

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