Kirkendall-Spring / View over the Campbell Lakes with stormy clouds at dusk, viewed from Walker Valley Overlook in Hart Mountain National Antelope Refuge, Oregon, USA, May 2013.

Andy Trowbridge / MacKinnon Pass, the highest point of the Milford track, Mount Hart (1769m) reflected in an alpine tarn, Milford Track, Fiordland National Park, Southland, South Island, New Zealand. November.

Kirkendall-Spring / Petroglyph at Petroglyph Lake in Hart Mountain National Antelope Refuge, Oregon, May 2013.

Tim Fitzharris / Pine River, Hart Ranges, British Columbia, Canada

Yva Momatiuk & John Eastcott / Cumulus clouds over prairie, Hart Mountain National Wildlife Refuge, Oregon

Tim Fitzharris / Hart River flowing over tundra beneath the Ogilvie Mountains, Yukon Territory, Canada

Michael Durham / Pronghorn Antelope (Antilocapra americana) male on grassland, Hart Mountain National Wildlife Refuge, Oregon

Michael Durham / Pronghorn Antelope (Antilocapra americana) male and female on grassland at sunrise, Hart Mountain National Wildlife Refuge, Oregon

Michael Durham / Pronghorn Antelope (Antilocapra americana) male on grassland at sunrise, Hart Mountain National Wildlife Refuge, Oregon

Michael Durham / Silhouette of Pronghorn antelope at sunset {Antilocapra americana} Oregon, USA Hart Mountain

Yva Momatiuk & John Eastcott / Juniper (Juniperus sp) in prairie with cumulus clouds above, Hart Mountain National Wildlife Refuge, Oregon