Jack Dykinga / Bighorm sheep (Ovis canadensis) males grouped together before the rutting season. Valley of Fire State Park, Nevada, USA, February.

Neil Aldridge / Five orphaned White rhinoceros (Ceratotherium simum) calves feed from a trough at dusk at the Rhino Revolution orphanage near Hoedspruit, South Africa. The mothers of these rhinos were killed by poach...

Donald M. Jones / American Bison (Bison bison) with grass on horns, National Bison Range, Montana

Ann & Steve Toon / Pied crows (Corvus albus) perched on horns of antelope skull. Zimanga Private Game Reserve, KwaZulu-Natal, South Africa.

Ingo Arndt / Racka sheep herd {Ovis aries} rare breed from Hungary

Ingo Arndt / Bison bull {Bison bison} Yellowstone NP, Wyoming, USA

Ingo Arndt / Alpine ibex male {Capra ibex ibex} Switzerland

Neil Aldridge / White rhinoceros (Ceratotherium simum) female 'Thandi' silhouetted against the sunset, Kariega Game Reserve. South Africa. Thandi's horns were taken in a brutal attack by poachers.

Neil Aldridge / Black rhinoceros (Diceros bicornis) feeding in early morning light, Kariega Game Reserve. South Africa.

Niall Benvie / Black faced sheep ram with twisted horns, Mull, Scotland, UK. January.

Wim van den Heever / Blue wildebeest (Connochaetes taurinus) herd silhouetted against the rising sun with clouds in the background. Greater Kruger National Park, South Africa

Edwin Giesbers / European bison (Bison bonasus) close up portrait showing horns, Zuid-Kennemerland National Park, the Netherlands. January. Reintroduced species.