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Dispatch from the field in Odzala National Park (Republic of Congo). I'm deep in the forest, in the middle of Odzala National Park in the Republic of the Congo. This magnificent park is being developed under the guidance of ECOFAC, a conservation programme funded by the European Union. Last year, the management team asked me to help with wildlife health issues and assist them with research efforts they were initiating. I made a quick trip last September to fit a forest elephant with a prototype satellite tracking collar and the system has proven itself to be quite effective.
Gorillas are susceptible to many human diseases, from such simple things as the cold or ‘flu to more serious diseases such as tuberculosis and Ebola. As this remote area becomes more accessible to researchers and tourists, a preventive approach to the health of the animals is needed. To accomplish this, first we need to know which diseases already exist in this "healthy looking" population of gorillas and which ones we need to ensure are not introduced by humans. For example, do they already have immunity to measles or is this something we need to make sure all of the park staff and their families are vaccinated for so they do not introduce it by accident? We cannot vaccinate all of the wild gorillas living in the forest, but we could potentially vaccinate all of the park workers and their villages. This would protect them and the gorillas. The famous chimpanzee researchers at Gombe Stream in Tanzania had the misfortune to witness polio introduced to the chimpanzees by non-vaccinated or possibly improperly vaccinated humans. To begin gathering the health information required to plan a sound program, we need to obtain blood samples from the gorillas. And of course, to do this I have to anaesthetise the animals. Anaesthesia of wild animals always involves some risk, not only to me and my team, but also to the gorillas. We have decided to start this project by working only on solitary males to avoid disrupting a family group just for our study. Gorillas live in tight but fragile social groups. The adult male will defend his females and young, but other males sometimes try to take over the family or at any rate make off with some of the females. Females are known to leave a male and wander off to join another male's group if the first one is not careful. If I put a big male to sleep for four to five hours, he may lose his whole family by the time he wakes up. If I dart a female, the male may not let us work on her or he may take the rest of the family and abandon her. To avoid these problems, not only do I have to find gorillas in the forest, but I have to find solitary or bachelor males.
Two of the males were in a bai about 200 yards long and 60 yards wide. We worked our way along one side, staying in the shadow of the forest to avoid each animal's gaze. We have to be as silent as possible while moving through the deep muck trying to avoid the sounds of squelching mud and crackling twigs and branches under foot. I leave the team behind when we get within fifty yards of the gorilla. Crawling on my hands and knees, moving the dart rifle along as carefully as I can without getting it buried in the mud or submerging it in water, I move as slowly as possible, close to the ground, in the hope of passing myself off as a motionless lump of insignificance. When the gorilla bends over to grab some vegetation or turns to look the other way, I slide forward a few feet, then freeze again. One gorilla was sitting in the shade of a big tree overhanging the bai while I was roasting out in the full, mid-day equatorial sun, hiding behind little clumps of scrub lining the edge of the bai. On a couple of other occasions they were in the full sun themselves, using wads of waterlogged vegetation to wet down their backs, shoulders and arms, while I wallowed in a flooded patch of forest nearby. The air-powered dart gun I'm using has a limited range, or more exactly, it's accuracy declines quickly with increasing range. It has the advantage of making very little noise and the light, plastic darts hit the animal with very low impact. But I need to be within 30 yards or so to maximise my chances of hitting the animal. That distance is about as close as I can get without being spotted by the gorilla; often they have already become suspicious but are still unsure of what I am. If I aim the dart rifle a foot or so above the animal, the dart arches nicely and strikes the animal in a thick muscle. So far I’ve successfully darted 4 solitary males. On another occasion a Hartlaub's duck spotted me and flew off screaming, scaring away the gorilla just before I took aim. Three of the gorillas hardly reacted to being darted, one pulled the dart out, smelled it, threw it on the ground and resumed feeding. Another ran about ten feet and then started looking in my direction until he fell asleep without ever bothering to touch the dart. The fourth moved about a hundred yards to the edge of the forest before going to sleep. Most likely, African honey bees and wasps give them occasional stings more dramatic than my little plastic darts. Within five minutes, the anaesthetic agent has done its job and the animal is "sleeping." It takes four of us to carry them to a shady place for their examination. I'm trying to use a light dose of anaesthesia to reduce the risk of an overdose, and two of the four gorillas have begun to wake up as we are working on them. This does cause a bit of excitement among the park guards when it looks as though a three hundred pound gorilla is about to wake up on them! But there has always been enough time for me to give a supplementary injection to get them back to sleep again.
As straightforward as the work appears to be, wild lowland gorillas have never before been examined like this to determine their health status, essentially because until now it has never been possible to approach them in the way that we are doing in Odzala. Decades of behavioural research has been conducted to observe their social nature and feeding habits, but no comprehensive effort to learn about their health or susceptibility to human disease impact has been made until now. These four gorillas are a first and with this effort we hope to gather information to guide us in the development of rational preventive strategies and guidelines for park staff, researchers, and tourists in order to protect the health of these magnificent great apes. If poaching pressure in neighbouring Cameroon continues at current levels, and the populations in north east Gabon fail to recover from their sudden disappearance in a large portion of their range, Odzala National Park may become the world's largest and most significant refuge for lowland gorillas left in the world. A population worth every effort to protect. Dr Billy
Karesh
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Odzala
is teaming with wildlife, and one of its remarkable qualities is the staggeringly
high density of western lowland gorillas. If a recently proposed Decree
for a five-fold extension to the park is signed by the President (bringing
the total area under protection to13.600 km2) current estimates indicate
that the extended park will harbour well over 30.000 gorillas. On this
trip, I came to help ECOFAC and park managers develop a health monitoring
program for the gorillas. Recent reports from the north east of neighbouring
Gabon, only 150 miles away, indicate that gorillas and chimpanzees disappeared
from thousands of square kilometres of forest at around about the same
time as the last Ebola virus outbreaks. Whether the two events are linked
is not clear but wildlife managers do not want to see a similar event
happen here and would like to have a better understanding of what is going
on.
Working
with three park guards and a few more assistants, we have staked out three
small clearings in the forest and are in touch with each other by radio.
These clearings (or bais as they are locally known) are often waterlogged
and covered with a carpet of sedges and other aquatic plants that the
gorillas like to eat. Several days of waiting produced family groups of
gorillas but no single males. But then our luck turned and on four days,
lone silverbacks (adult males with the mature silver-grey saddle of hair
on their back) pitched up in the clearing. All three have been at the
far end of the clearing, near the forest edge, feeding on the aquatic
plants. They have an interesting technique, plucking a small mat from
the surface using their massive hands, 3-4 times bigger than mine, giving
the vegetation a little shake with a few deft flicks of the wrist. They
then drag the roots back and forth across the surface of the little streams
running through the clearings, shake the mat out again and pop the mass
it into their mouths, biting off the white roots and discarding and the
green tops. 
The
examination involves a full physical examination, just as you or I would
receive at our physician's office. I listen to their hearts for any sounds
of abnormalities, check their lungs, and examine their eyes, ears, noses,
mouths, teeth, etc. I take blood samples for laboratory testing, and faecal
samples to check for internal parasites. With a cargo net, a long pole
cut from a nearby sapling and two hanging scales, we weigh the animals.
Of the four so far, they have ranged from 270 to 320 pounds. They also
showed evidence of interesting illnesses. The lightest one was covered
from the waist down with a dermatitis that looked like a severe ringworm
infection in humans. Big patches of skin were peeling off his legs and
feet and his lower belly and groin must have been infected for so long
that the skin had lost it's normal black coloration and was now pinkish-white
(photo). Another animal had ulcers on his face that look like an infection
of humans called "Yaws" (photo). It's actually a common human
disease in Central Africa, and probably introduced to some gorilla populations
by people centuries or millennia ago. When the procedures are finished,
we sit quietly nearby for several hours, waiting for the gorilla to wake
up gradually from anaesthesia and ensuring that he is not preyed upon
by a leopard while still groggy. Later, back at camp I will process the
samples using portable lab equipment. Using a tank of liquid nitrogen
I will be able to keep the samples frozen at 280 degrees below zero (-180C).