Ingo Arndt / Golden monkey (Cercopithecus mitis kandti) looking down from tree, Parc National des Volcans, Rwanda

Ingo Arndt / Mountain gorilla portrait (Gorilla gorilla berengeii) Parc des Volcans, Rwanda

Ingo Arndt / Mountain gorilla (Gorilla gorilla berengei) yawning, showing stained teeth, Parc des Volcans, Rwanda

Ingo Arndt / Clouds capping volcano crater, Parc des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother lying on back and holding baby age one year. Parc National des Volcans, Rwanda. Endangered species

Cyril Ruoso / Mountain Gorilla (Gorilla gorilla beringei) female with her three month old newborn, Parc National Des Volcans, Rwanda

Cyril Ruoso / Mountain Gorilla (Gorilla gorilla beringei) close-up portrait of a silverback in the rain, Parc National Des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) silverback feeding, Parc National des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Christophe Courteau / Mountain Gorilla (Gorilla beringei) female holding baby in dense vegetation in Volcanoes National Park, Rwanda, at an altitude of 3000m, short dry season, February

Christophe Courteau / Mountain gorilla (Gorilla beringei) baby in mother's arms. 3000 metres above sea level in Volcanoes National Park, Rwanda. Short dry season, February