Kahuzi-Biega is the only place on Earth where you can walk up to a habituated family of Grauer's gorillas. This is the eastern lowland gorilla, the largest primate alive, found in the forests of eastern DR Congo and nowhere else; a silverback here runs to two hundred kilograms. Trackers go out at dawn to find the family, then lead you off the path into nettles, vines and mud, reading last night's nests and the stems chewed that morning. The forest tells them where the gorillas slept, not where they are now, so the walk can take twenty minutes or most of a morning. When the family is found the clock starts. The hour you get is spent a few metres from animals that carry on eating, dozing and grooming as if nobody had come. The youngsters swing and test branches around the edges, and the silverback keeps one eye on all of it, and on you.
What they eat has changed under them. The gorillas here once spent three months of the year gorging on fresh bamboo shoots. In the mid-1990s the bamboo died back across the park and never fully returned, so they strip far more bark than they used to. The park's own history is harder than the forest looks. Its boundaries were drawn around the Batwa, who were living in it and were evicted without being asked. In 2022 an African human-rights body found that this broke the law and ordered reparation. Whether anyone can trek here depends on the security situation rather than the season, and only the park authority can answer that. Away from them a four-hour trail climbs Mount Kahuzi to 3,308 metres, out of bamboo into heather and tree groundsel, with Lake Kivu and Bukavu below to the east. One silverback in this forest has no family at all. A poacher's snare took Mugaruka's hand when he was young, so he has never been able to hold a group against rival males. He keeps his distance from the younger silverbacks and ranges alone, and the rangers still follow him every day.