I’m one of eight visitors — the maximum allowed into Cyamdongo Forest on any day — participating in a group trek in the hope of sighting at least one of the 25 chimpanzees that live in this farmland-surrounded fragment of mountain rainforest.
During the pre-trek briefing, Kambogo, a local naturalist and guide, points out that spotting chimpanzees, with whom we humans share 98% of our DNA, cannot be guaranteed. They nest at different sites every night and are easiest to spot as they de-nest and start foraging for food; this is why we’re out so early.
Ahead of us, trained trackers are already looking for signs — including nests and fresh droppings — and listening out for calls to lead us to the chimpanzees. Although Cyamdongo has an area of just 1.5 sq miles, the density of tropical trees, foliage and liana vines makes sightings tricky.
Chimpanzee tracking started here in 2005, the year Nyungwe was officially declared a national park, and the trail leading into the shadowy greenery is worn flat and precariously slippery in places. Even in good walking boots I struggle to stay on my feet, but the guides, all of them wearing rubber Wellington boots, are surefooted and offer support.
Somewhere up ahead, screaming, whooping and a series of excited, short cries reverberates through the forest, jolting me alert. “These are chimpanzee calls,” says Kambogo.
A tracker returns and tells us to get off the trail; chimpanzees are heading towards us and may well pass by, using the path. We move into the undergrowth and after a couple of minutes a male chimp appears, walking along the trail, supporting himself on his knuckles. He spots us and clearly doesn’t like the idea of getting too close; he scampers off.
For the next couple of hours, we search in vain for further chimpanzee sightings but do see L’Hoest and mona monkeys in the branches above us. The guides seem unimpressed — their focus is chimps — but watching the monkeys feeding and idly grooming each other, from a distance of less than 10 metres, is enchanting.
Despite being reasonably fit, I’m finding the going exhausting. We’re at an altitude of about 5,250ft (one mile) above sea level and the terrain is hilly. Nonetheless, the trackers think I’m doing OK and suggest I follow them into moist hillside undergrowth, where I have to duck and weave between branches.
We hear whooping nearby. “It’s the alpha male calling the rest of the group to him,” explains a guide. At the next clearing, he points up. The powerfully built alpha male sits there in a tree and we look on as he feeds. I’m breathless. Getting here was strenuous but it’s partially down to the excitement of being this close to a great ape in its natural habitat.