Mountain gorillas are back from the brink. But what happens if they run out of room?

Mountain gorilla numbers have quadrupled to at least 1,000 since the 1970s, thanks to conservation efforts and sharing tourist income with local communities Photograph: Badru Katumba/The Guardian

It is sunrise on mount Muhabura, an inactive volcano on the Ugandan-Rwandan border, and Dr Benard Ssebide is in a rush to find a family of mountain gorillas before the tourists arrive. A mass of ferns, vines and thistles encroaches on the path, and the guides hack through brambles with machetes. Above, the forest whistles in the wind, glowing in the morning light.

“The higher you go, the more the mountain pushes back,” Ssebide says, pausing for breath.