Andy Rouse / Mountain gorilla (Gorilla beringei) silverback in Susa group, Parc National des Volcans, Rwanda

Andy Rouse / Mountain gorilla (Gorilla beringei beringei) silverback male portrait, Volcanoes NP, Virunga Mountains, Rwanda

John Sparks / David Attenborough with mountain gorillas, on location during filming for BBC 'Life on Earth' series in Rwanda 1978

Eric Baccega / Portrait of male silverback Mountain gorilla (Gorilla beringei beringei) feeding. Bwindi Impenetrable Forest National Park, Uganda, Africa

Eric Baccega / Mountain gorilla (Gorilla beringei beringei) silverback male, portrait, member of the Nyakagezi group, Mgahinga National Park, Uganda.

Oriol Alamany / Mountain gorilla (Gorilla berengei) female holding newborn baby, from Titus Group in the Visoke rainforest, Volcanoes National Park, Rwanda, August

Eric Baccega / Mountain gorilla (Gorilla beringei) juvenile aged 2 years, hanging from branch, member of the Nyakagezi group, Mgahinga National Park, Uganda. January.

Mary McDonald / Adult Mountain gorilla (Gorilla beringei beringei) holding baby, Hirwa group, Volcanoes National Park, Rwanda

Pedro Narra / Mountain Gorilla (Goriila beringei) resting, Volcanoes National Park, Virunga Mountains, Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei), silverback and juvenile son. Volcanoes National Park. Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei), dominant silverback in forest clearing. Volcanoes National Park, Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei) blackback, juvenile male demonstrating power. Volcanoes National Park, Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei) blackback, juvenile male demonstrating power. Volcanoes National Park, Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei) silverback sitting on boundary wall between Volcanoes National Park and a Potato crop, looking into valley. Area to be restored to forest. Rwanda.

Christophe Courteau / Mountain gorilla (Gorilla beringei beringei) female with baby, portrait. Volcanoes National Park, Rwanda.

Mary McDonald / Mountain gorilla (Gorilla beringei beringei) female with baby age, 4 months, Volcanoes National Park, Rwanda

Eric Baccega / Mountain gorilla (Gorilla beringei beringei) juvenile female stretching hand out towards camera, member of the Kabirizi group, Virunga National Park, North Kivu, Democratic Republic of Congo, Africa,...

Jabruson Motion / National park guards and trackers transporting a dead silverback Mountain gorilla (Gorilla beringei beringei), Bukima, Virunga National Park, Democratic Republic of Congo, 1996.

Jabruson Motion / Three juvenile Mountain gorillas (Gorilla beringei beringei) resting in vegetation, rolling and playing before approaching camera, Bukima, Virunga National Park, Democratic Republic of Congo, 1996.

Jabruson Motion / Close-up of a male Mountain gorilla (Gorilla beringei beringei) looking at camera, pulls off lens component, Bukima, Virunga National Park, Democratic Republic of Congo, 1996.

Jabruson Motion / Close-up of a female Mountain gorilla (Gorilla beringei beringei) feeding, gets up and rolls into new resting position near other family members, Bukima, Virunga National Park, Democratic Republic of...

Jabruson Motion / Female Mountain gorilla (Gorilla beringei beringei) getting up from resting and eating, twirls around before settling down into a new resting position, Bukima, Virunga National Park, Democratic Republ...

Jabruson Motion / Silverback Mountain gorilla (Gorilla beringei beringei) and family resting in vegetation, with a juvenile peering into the camera lens Bukima, Virunga National Park, Democratic Republic of Congo, 1996...

Jabruson Motion / Close-up of a male Mountain gorilla (Gorilla beringei beringei) and juvenile resting, captivated by reflection in camera lens, knocks juvenile over, Bukima, Virunga National Park, Democratic Republic...

Jabruson Motion / Close-up of a female Mountain gorilla (Gorilla beringei beringei) looking at camera, scratches face, Bukima, Virunga National Park, Democratic Republic of Congo, 1996.

Jabruson Motion / Close-up of a male Mountain gorilla (Gorilla beringei beringei) looking at camera, with another male approaching from behind, beats chest displaying, Bukima, Virunga National Park, Democratic Republic...

Jabruson Motion / Wide angle shot of a juvenile Mountain gorilla (Gorilla beringei beringei) swinging from a branch and looking at camera, with a silverback nearby, Bukima, Virunga National Park, Democratic Republic of...

Jabruson Motion / Close-up of a tracker, shot pans to a silverback Mountain gorilla (Gorilla beringei beringei) looking at camera, Bukima, Virunga National Park, Democratic Republic of Congo, 1996.

Christophe Courteau / Female Mountain gorilla (Gorilla beringei beringei) playing with baby, Volcanoes National Park, Rwanda.

Fiona Rogers / Mountain gorilla (Gorilla gorilla beringei) female portrait, member of 'Humba' group . Virunga National Park, Democratic Republic of Congo, March.

Fiona Rogers / Mountain gorilla (Gorilla gorilla beringei) female portrait , part of the 'Munyanga' group. Virunga National Park, Democratic Republic of Congo, March.

Fiona Rogers / Mountain gorilla (Gorilla gorilla beringei) silverback male feet, member of 'Humba' group. Virunga National Park, Democratic Republic of Congo, March.

Fiona Rogers / Mountain gorilla (Gorilla gorilla beringei) infant portrait, member of 'Humba' group. Virunga National Park, Democratic Republic of Congo, March.

Fiona Rogers / Mountain gorilla (Gorilla gorilla beringei) female portrait, member of 'Humba' group . Virunga National Park, Democratic Republic of Congo, March.

Anup Shah / Mountain gorilla (Gorilla gorilla beringei) infant portrait, member of 'Humba' group. Virunga National Park, Democratic Republic of Congo, March.

Jabruson Motion / Silverback Eastern lowland gorilla (Gorilla beringei graueri) 'Chimanuka' getting up to reach for a Myrianthus holstii fruit, nearby juvenile takes a leaf from his rear, Kahuzi-Biega National Park, So...

Jabruson Motion / Close up portrait of a female Mountain gorilla (Gorilla beringei beringei) seen through foliage, with an infant appearing and looking at the camera, Bukima, Virunga National Park, North Kivu, Democrat...

Jabruson Motion / Close up of a baby Mountain gorilla (Gorilla beringei beringei) looking at the camera before leaving the frame, part of the À™NyakamweÓ family group, Bukima, Virunga National Park, North Kivu, Democ...

Jabruson Motion / Silverback Mountain gorilla (Gorilla beringei beringei) from the 'Nyakamwe' family group looking at the camera before sitting back, Bukima, Virunga National Park, North Kivu, Democratic Republic of Co...

Jabruson Motion / Female Mountain gorilla (Gorilla beringei beringei) with juvenile walking through foliage before a silverback enters the frame and looks at the camera, Bukima, Virunga National Park, North Kivu, Democ...

Jabruson Motion / Two juvenile Eastern lowland gorillas (Gorilla beringei graueri) playing, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Silverback Eastern lowland gorilla (Gorilla beringei graueri) 'Chimanuka' grooming a juvenile female, shot pans to reveal other juveniles playing nearby, Kahuzi-Biega National Park, South Kivu, Democr...

Jabruson Motion / Close up of a silverback Eastern lowland gorilla (Gorilla beringei graueri) 'Chimanuka' grooming a juvenile female, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Close up of a silverback Eastern lowland gorilla (Gorilla beringei graueri) 'Chimanuka' grooming a juvenile female, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Juvenile Eastern lowland gorilla (Gorilla beringei graueri) playing with a stick and looking at the camera, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Juvenile Eastern lowland gorilla (Gorilla beringei graueri) looking around, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Close-up portrait of a juvenile Eastern lowland gorilla (Gorilla beringei graueri), Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.

Jabruson Motion / Juvenile Eastern lowland gorillas (Gorilla beringei graueri) with a missing hand, rolling forward to join another, Kahuzi-Biega National Park, South Kivu, Democratic Republic of Congo.