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

Konrad Wothe / Showreel of Male Chimpanzees (Pan troglodytes) attacking the alpha male of their troop, Mahale Mountains National Park, Tanzania.

Konrad Wothe / Male Chimpanzees (Pan troglodytes) attacking the alpha male of their troop, Mahale Mountains National Park, Tanzania.

Fiona Rogers / Eastern chimpanzee (Pan troglodytes schweinfurtheii) alpha male 'Ferdinand' aged 20 years, females Nuru' aged 22 years and 'Nasa' aged 24 years calling. Gombe National Park, Tanzania. June 2012.

Cyril Ruoso / Drill (Mandrillus leucophaeus) alpha male calling, Pandrillus Drill Sanctuary, Cross River State, Nigeria

Cyril Ruoso / Drill (Mandrillus leucophaeus) adult female grooming alpha male, Pandrillus Drill Sanctuary, Nigeria

Anup Shah / Western chimpanzee (Pan troglodytes verus) infant male 'Flanle' aged 3 years acting aggressively towards alpha male 'Foaf' aged 30 years, Bossou Forest, Mont Nimba, Guinea. January 2011. Sequence 4...

Danny Green / 2020VISION / Red deer (Cervus elaphus) dominant stag at rut, Bradgate Park, Leicestershire, England, UK, November

Anup Shah / African Lion pride male (Panthera leo) head portrait, low angle, Masai Mara National Reserve, Kenya. February

Suzi Eszterhas / Alpha male Chimpanzee (Pan troglodytes) self grooming. Tropical forest, Western Uganda.

Anup Shah / Alpha male Chimpanzee 'Frodo', 26-years-old, feeding on leaves {Pan troglodytes schweinfurtheii} Kasekela community, Gombe NP, Tanzania. 2002. Chimps have learnt that certain leaves can be used to tre...