Dr. Potts’ final notes from Uganda

I’m now sitting in the Entebbe airport, waiting for my flight out of the country, back to the US. For my last post, I thought I would say something about the conservation status of chimpanzees in general, and that of chimpanzees at Ngogo in particular. This is an issue I think about often, as I’ve watched the precipitous decline of chimpanzee populations throughout equatorial Africa over the last decade or so that I’ve been studying this species, while at the same time witnessing the fairly dramatic increase in community size and density of my study community at Ngogo. Like virtually all the great apes, chimpanzees are considered endangered – certain populations, or “subspecies”, are considered critically endangered and will likely disappear within my lifetime. The fate of wild chimpanzees will be dictated in the near future by the effects of several interrelated factors: habitat loss (both legal and illegal), bushmeat hunting/poaching, and episodic disease outbreaks. Logging and mining operations have decimated chimpanzee habitats (the species is unlucky to inhabit areas rich in both precious hardwoods and rare minerals), especially since the discovery of oil in several African countries with large chimpanzee populations. While some of my work in the past has shown that low-intensity selective logging can be compatible with chimpanzee conservation, large-scale clear-cutting for commercial timber or mineral extraction certainly cannot. In many African countries in which timber operations have opened up access to forests inhabited by chimpanzees (and other primates), illegal bushmeat hunting, usually through the use of wire snares in which chimpanzees become entangled, has increased dramatically. There is a misperception among many in the western world, however, that the bushmeat “issue” is one that stems primarily from the need for local villagers in areas occupied by chimpanzees and other primates to obtain a steady source of protein. If this were the case, the problem could, in theory, be easily solved by providing alternative sources of protein to these populations. The truth, it turns out, is that the non-sustainable poaching of chimpanzees for bushmeat is largely driven by large commercial markets operating out of large, metropolitan areas, including some in the “developed world” (even the US). A large supply of bushmeat was recently confiscated, for example, at Charles De Gaulle airport in Paris, and not long before that at London’s Heathrow and New York’s JFK airports. The consumption of bushmeat is associated with cultural status in many African cultures, and wherever the diaspora of sub-Saharan African elite culture spreads, whether it be Nairobi or New York, there is likely to be an underground market for bushmeat in those areas. And, as long as that market exists, populations of chimpanzees and other unfortunately easily-caught primates will continue to decline. Finally, the disease issue. This is one that has only relatively recently emerged, largely because many of the diseases that currently decimate chimpanzee populations, primary among them the Ebola virus, only recently began to afflict chimpanzees (and humans, for that matter, who are as susceptible, if not more so, to Ebola as chimps). For as terrifying and dangerous a disease as Ebola is (with upwards of 95% mortality in some cases, it is among the most virulent of all known diseases afflicting primates), we know surprisingly little about it. For example, we think that its primary host is one of a number of species of fruit bat that live in the same forests as chimpanzees (and, in some cases, gorillas), and that apes become infected by using the feeding tree as a bat carrying the virus, but there is not really all that much evidence to strongly support this. What we do know is: 1) the virus is easily transmitted between humans and chimpanzees, primarily through contact with bodily fluids, and 2) once a chimpanzee in a particular population is infected, it spreads extremely rapidly and, as I just mentioned, has a very high mortality rate. Recent Ebola outbreaks have virtually destroyed otherwise thriving chimpanzee populations, for example the previously very large population in the Tai Forest in Côte d’Ivoire in far Western Africa. Ebola is almost single handedly responsible for giving western lowland gorillas the unenviable “Critically Endangered” designation on the IUCN’s Red List of Threatened and Endangered Species. But it is not just the scary, horrifyingly grim pathogens like Ebola that threaten the long-term viability of chimpanzee populations. Seemingly far less insidious diseases, such as simple upper respiratory tract infections, which may have little to no external manifestations in humans, can wreak havoc on a chimpanzee population in which individuals lack immune responses to such infections. In Gombe National Park, for example, where Jane Goodall’s famous study of chimpanzees was first initiated in the early 1960s and continues today, retrospective analysis of major mortality events in the chimpanzee population there showed that there was a very high probability that the deaths were caused by respiratory illnesses spread from humans to chimps. As researchers, we come into fairly close contact with our study animals, and we need to be cognizant of the fact that they can easily become infected by a simple cold virus that we may be carrying, and that such a virus can be much more dangerous to their health than to ours.


All of these factors are working in consort have led to a major decline in wild chimpanzee numbers over the last decade. However, as I mentioned at the beginning of this post, the chimpanzees at my study site, Ngogo, have not only avoided such decline but have positively thrived over this same period. When I first started studying chimpanzees at Ngogo in 2002, there were about 140 chimps there (already more than twice the size of the next largest community anyone knew of). Today there are almost 200, nearly 4 times the size of the next largest known community. This is astounding, considering what is happening to chimpanzees elsewhere. I look at the chimpanzee community at Ngogo with a sense of guarded optimism, however, for its “success” comes with some caveats. The forest at Ngogo has been relatively unaffected by resource extraction in the past, but massive reserves of oil were recently discovered in western Uganda and there is no reason to believe these reserves are not going to be exploited to their fullest extent, and any forest that must be cleared in the process will be considered collateral damage. Chimpanzees at Ngogo have not been directly targeted for bushmeat, largely because of a taboo that exists in the cultures of the local Batoro and Bakiga tribes that surround Kibale National Park against eating primates, but there is evidence that Congolese refugees fleeing civil war in eastern Democratic Republic of Congo have moved into the area east of the Rwenzori Mountains, just outside Kibale, and have started poaching chimpanzees (no such taboo against eating primates exists in these cultures). The chimpanzees at Ngogo have not been affected by any major disease outbreaks in historical times, but Ebola outbreaks have hit several human populations not far outside of Kibale, and there is no reason to think that the virus cannot spread into the park (particularly if people poach and eat chimpanzees).


Given all that, I don’t want to end this blog on a pessimistic note. Despite all these caveats, Ngogo is still the best place on Earth to see and study chimpanzees. There is no other place in the world where you can hike into the forest and see upwards of a hundred chimpanzees in the same area. It is an experience I can’t adequately describe, except to say that I feel privileged to have the opportunity to witness such a scene. I hope you’ve enjoyed reading this blog as much as I’ve enjoyed writing it. I’m always happy to share photos and stories with anyone who’s interested, so once I’m back on campus feel free to track me down. I’ll be the one with the beard that looks like a chimp’s.