Along the borders of Uganda, Rwanda and the DRC lies the Virunga national park – the home of mountain gorillas. Back in 1970s there were only a few hundred of these gorillas left. Yet today the community is thriving with more than 1,000.

Patrick Greenfield, the Guardian’s biodiversity reporter, headed up into the Virunga mountains, guided by wildlife vets, to find out how they achieved this rare and extraordinary conservation success. He tells Annie Kelly how the gorillas have been protected in such a volatile area.

Photograph: Badru Katumba/The Guardian