Conserving Gorillas - Five Questions

In thinking about conservation of a species, I find that five questions are useful. Why conserve, i.e. what threats does the species face? What should be conserved, i.e., what populations should we concentrate on? How many animals should be conserved to protect a viable population for perhaps a millennium? Where should we protect that number? And finally, how should we manage the conservation?

Why Conserve Gorillas?
Like so many other species, gorillas are threatened by increasing destruction of their habitat and its environs. Part of the increase in destruction is caused by an increasing human population needing more land to support itself. A strong correlation exists between human density and deforestation rates, including across the nine African countries that harbor gorillas - and the human population is increasing more rapidly in sub-Saharan Africa and in host countries of gorillas (over 2% annually) than anywhere else in the world. Add the world's increasing consumption of forest products (a five-fold increase in the last half century from gorilla countries), and it is difficult to see how any forest is going to remain outside of protected areas.
The ravages of the viral infection, Ebola, on western gorilla populations has received much attention recently. This disease and the bushmeat trade might have more than halved populations in some areas. The bushmeat trade is exacerbated by commercial logging. Hard on the heels of the logging roads, penetrating deeper into the forests than any other form of exploitation, comes small-scale settlement and commercial hunting. Concrete evidence of the susceptibility of gorillas to hunting comes from the extraordinary countrywide foot-survey of Gabon conducted 25 years ago by Caroline Tutin and Michel Fernandez. They estimated a 70% drop in gorilla numbers in heavily hunted areas, and back then the bushmeat trade was not as intense and widespread as now.

What Gorillas to Conserve?
To avoid taxonomic argument, I write as if only one species (superspecies) of gorilla existed, and I refer to the sub-populations by their common names, not their scientific names.
Perhaps the first source for anyone wondering what species need conserving globally is the IUCN Red List of Threatened Species.
According to the Red List for 2007, the Cross River gorillas of Nigeria and Cameroon are Critically Endangered. The population numbers less than 250 adults, splintered among a number of sub-populations; it is surrounded by some of the densest human populations on the continent; and despite increased protection, it seems likely that the population is decreasing. It used to be the case that 300 km separated this from the next western gorilla population, but in 2003, reports were published of a population just north of the Sanaga River of Cameroon, half way between Cross River and the next western population. The forests in which this Ebo population live are extensive, but heavily hunted.
Western gorillas are still by far the most numerous - several tens of thousands - despite heavy casualties from Ebola and the bushmeat trade. Nevertheless, fears that the population will soon experience, or might already have experienced, the criterion crash of 80% over three generations (about 100 years) have put it into the Critically Endangered category in the 2007 Red List.
To give some perspective on that status, while a total of about 30,000 western gorillas might exist in 6 widely separated protected areas, each of 5,000 km² or more, the population of the critically endangered kakapo (a New Zealand parrot) numbered just 90 individuals in 2005.
The eastern lowland, or Grauer's, gorillas of eastern Democratic Republic of the Congo are classified on the Red List as Endangered. There might be about 15,000 of them, but the chaos in eastern Congo must be sorely affecting them. The fact that 4 million people died THERE from killing, mutilation and starvation in the 5 years to 2004 indicates such a complete civil breakdown that it seems very possible that the gorilla population will soon meet the Critically Endangered criterion of an 80% decline in numbers in the next century.
The Red List is currently recalculating the status of the 700 or so mountain gorillas. I have argued for some time now that mountain gorillas need to be downgraded to Endangered from Critically Endangered. A Critically Endangered listing requires an observed, projected, or inferred declining population. Neither the Bwindi nor the Virunga population of mountain gorillas is declining. Indeed, the Virunga population has been increasing ever since the 1980s, when was begun the successful tourism program, which the Red List states is a threat to the Virunga gorillas. Data to substantiate this increase has long been published, and we now know that the Bwindi population is either increasing or stable.
However, the recent (October 2007) rebel take-over of the entire Congolese sector of the Virunga Volcano protected area of Congo, Rwanda and Uganda does not bode well for the Virunga population, given so many killings of gorillas by rebels in the region. The appalling civil situation in eastern Congo is so long-standing, so ignored by the rest of the world, so apparently intractable, that I am going to have to change my mind about the future trends of the Virunga population.
If 4 million people there can die there in 5 years, why not a few hundred gorillas?

How Many Gorillas Should We Conserve?
A variety of analyses, both biogeo-graphic and genetic, indicate that, very roughly, a population of 5,000 large-bodied animals might allow persistence for a millennium: 5,000 gorillas need 5,000 km² of good habitat. One population of 5,000 gorillas is not sufficient, however. The apparent near-eradication of gorillas by Ebola over much of one of the largest and apparently safest national parks, Odzala in the Repupblic of Congo, shows how important it is to have more than one population fully protected.

Where Should Gorillas Be Conserved?
Conservation does not have enough money or people to do all that is necessary. Therefore, a sensible rule of thumb might be to concentrate at any one time on areas or populations in the greatest need of protection, and areas or populations on which conservation effort would be most efficiently expended.
Need: While populations of less than several thousand gorillas are probably not safe for millennia, nevertheless, in order to ensure protection of variety, the westmost and eastmost populations of gorillas (Cross River, mountain) should surely continue to be protected, small as the populations are.
Efficient expenditure: Seven protected areas in Africa cover 5,000 km² or more each, and might each contain, or might have contained, over 5,000 gorillas. Six of them are in 4 West African nations: Cameroon, Central African Republic, Republic of Congo, and Gabon. The seventh is in eastern Congo. These seven protected areas are separated one from another by scores of kilometers.

How Should We Conserve Gorillas?
Africa is extremely poor, and its people in dire straits. Perhaps half of the people in gorilla countries are subsisting on less than a dollar a day, and have an expectation of healthy life of only about 40 years (compared to the majority-world average of about 55 years). Therefore, funding for conservation must come largely from outside the continent. Given what minority-world governments spend on their armed forces and on subsidizing environmental damage, plenty of money is available.
I have already identified in the previous section where conservation effort should be concentrated. The pejorative term "paper parks" is often applied to majority-world protected areas. However, not only do we know that
protection can be successful in majority-world countries, but the average size of protected areas is greater in those countries than in minority world countries. For instance, sub-Saharan Africa's median protected area is 205 km², compared to Europe's 6 km². Moreover, several African countries spend (or spent) on their protected areas a greater proportion of government expenditure than do/did western countries.

Conclusion
Stories in the media of the gorilla's demise in the wild in the next 25 years are exaggerated. The gorilla is going to be around for much longer than the Sumatran orangutan. Nevertheless, over the next 100 years, a huge crash in gorilla numbers outside of reserves is bound to occur.
At the same time, the dedication, even unto death, of some of Africa's park guards and other protectors of wildlife, the willingness of many of Africa's leaders to establish as national parks huge swathes of their territory, their willingness to expend a greater proportion of their country's income on protection of wilderness than do many developed nations, and the remarkable story of the success of mountain gorilla conservation in eastern Africa are grounds for hope.

Alexander H. Harcourt

This article is based on Part 1 of chapter 14 of Gorilla Society by myself and Kelly J. Stewart, University of Chicago Press, 2007. Substantiating data and sources for the contents of this article can be found there. Our book benefitted enormously from commentary by many friends and colleagues, but particularly from Martha Robbins.

Prof. Alexander H. Harcourt, of the Dept. of Anthropology, University of California, Davis, was born in Kenya, and began a lifetime of studying gorillas in Africa in 1971, in Rwanda and Democratic Republic of the Congo. More recently he has also been studying gorillas in Nigeria and Uganda.

Gorillas in general - overview

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