In pictures: Gorilla guardians

The rangers can identify each gorilla by name, by memorising the markings on their face. A log book is kept with facial drawings of each individual.

The rangers let the gorillas know they are approaching by making a noise understood and agreed by both of them. A way of saying – it is ok, we are here as friends.

“When we first find a new family, we spend more than a month going no closer than 100m,” Mr Kambale says.

“After a year, we can go close and bring tourists."