Edwin Giesbers / RF- Sumatran tiger (Panthera tigris sumatrae) close-up head portrait, captive. (This image may be licensed either as rights managed or royalty free.)

Andy Rouse / RF- Siberian Tiger (Panthera tigris altaica) walking in snow. Captive. Endangered species. (This image may be licensed either as rights managed or royalty free.)

Andy Rouse / RF- Siberian Tiger (Panthera tigris altaica) walking in snow. Captive. Endangered species. (This image may be licensed either as rights managed or royalty free.)

Edwin Giesbers / RF- Head portrait of Siberian tiger (Panthera tigris altaica) lying in foliage, captive. (This image may be licensed either as rights managed or royalty free.)

Edwin Giesbers / RF- Portrait of Siberian tiger (Panthera tigris altaica) walking in snow, captive. (This image may be licensed either as rights managed or royalty free.)

Andy Rouse / RF- Snow leopard (Panthera uncia) lying on snow, USA. Endangered species. (This image may be licensed either as rights managed or royalty free.)

Andy Rouse / RF- Snow leopard (Panthera uncia) in high alpine habitat, captive, USA. Endangered species. (This image may be licensed either as rights managed or royalty free.)

Nick Garbutt / RF- Male Bengal Tiger (Panthera tigris tigris) face portrait in undergrowth, Kanha National Park, Madhya Pradesh, India. Endangered species. (This image may be licensed either as rights managed or roy...

Tony Heald / RF- Tiger portrait (Panthera tigris) Bandhavgarh National Park, India. Endangered species. (This image may be licensed either as rights managed or royalty free.)

Lynn M Stone / RF- Siberian tiger (Panthera tigris altaica) in snow, captive. (This image may be licensed either as rights managed or royalty free.)

Staffan Widstrand / RF- Young male Bengal tiger, head portrait in profile (Panthera tigris tigris). Bandhavgarh National Park, India. (This image may be licensed either as rights managed or royalty free.)