Jeff Foott / Mule-ears (Wyethia amplexicaulis) flowers at the The Organ, Arches National Park, Utah

Shattil & Rozinski,Shattil & Rozinski / Mule deer (Odocoileus hemionus), with the Denver skyline and Rocky Mountains in the background, Denver, Colorado, USA, November.

David Noton / Woman and man with livestock walking along path, Isla del Sol, Lake Titicaca, Bolivia, December 2009

Christophe Courteau / Pantaneiros horsemen leading cattle and horse livestock along the Transpantaneira, Pantanal, Brazil, July 2008

Konstantin Mikhailov / Mule Deer (Odocoileus hemionus columbianus) female running, rear view. Olympic NP, Hurricane Hill, Washington, USA, October 2009.

Floris van Breugel / Dogwood (Cornus nuttallii) in bloom amongst Giant Sequoia trees (Sequoiadendron giganteum) and two Mule deer (Odocoileus hemionus), Sequoia and King's Canyon National Parks, USA. June. Veolia Environn...

Donald M. Jones / Mule Deer (Odocoileus hemionus) buck, western Montana

Shattil & Rozinski / Mule deer (Odocoileus hemionus) buck, Cherry Creek State Park, Denver, Colorado, USA

Bernard Castelein / Male Mule deer portrait (Odocoileus hemionus) Olympic NP, Washington, USA

Rolf Nussbaumer / Mule deer {Odocoileus hemionus} buck portrait, Grand Teton NP, Wyoming, USA

TOM MANGELSEN / Mule deer (Odocoileus hemionus), female nuzzling young. Montana, USA

Juan Manuel Borrero / Mule - offspring of male donkey and female horse - Spain