Roland Seitre / Park ranger in his vehicle. Northern Rangelands, Ishaqbini Reserve, Kenya, 2009.

Mark Carwardine / Black rhinoceros (Diceros bicornis) calf with game ranger, Endangered species, Mkhaya Game Reserve, Swaziland

Mark Carwardine / Game ranger and vet checking on a Northern white rhinoceros (Ceratotherium simum cottoni) after initial release into the wild, Ol Pejeta Conservancy, Kenya, June 2010, Extinct in the wild, only eight...

Mark Carwardine / Game ranger checking on a Northern white rhinoceros (Ceratotherium simum cottoni) after initial release into the wild, Ol Pejeta Conservancy, Kenya, June 2010, Extinct in the wild, only eight left in...

Staffan Widstrand / Wildlife ranger with gun silhouetted against sunset sky, Selous Game Reserve, Tanzania.

Onne van der Wal / Local game ranger / guide, Motswari private game reserve, northern South Africa.

Mark Moffett / Asiatic Brush-tailed Porcupine (Atherurus macrourus) atop cage about to be released back into the wild by rangers, Tam Dao National Park, Vietnam