Ole Jorgen Liodden / Arctic tern (Sterna paradisaea) attacking an Arctic Fox (Vulpes / Alopex lagopus) protecting its nest site, Spitsbergen, Svalbard, Norway. Highly commended, MAMMALS, GDT 2011 competition

Chase Dekker / Moose (Alces alces) bull in tundra, Mount Rundle, Banff National Park, Alberta, Canada

Yva Momatiuk & John Eastcott / Heather (Calluna sp) flowering in tundra, Skaftafell National Park, Iceland

Yva Momatiuk & John Eastcott / River with waterfalls in tundra, Klifbrekkufossar Waterfall, Mjoifjordur, Iceland

Donald M. Jones / Caribou (Rangifer tarandus) bull in tundra, Denali National Park, Alaska

Markus Varesvuo / Snowy owl (Bubo scandiaca) female sitting among snow covered vegetation on ground, Canada February

Danny Green / Moose Bull (Alces alces) walking in forest clearing, Denali National Park, USA, September

Donald M. Jones / Bighorn Sheep (Ovis canadensis) rams in tundra, western Canada

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bull in tundra, central Alaska

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bull in tundra, central Alaska

Sven Zacek / Autumn trees on the Rapa River Delta, aerial view, Rapadalen Sarek National Park, Sweden, September 2009.

Mark Raycroft / Willow Ptarmigan (Lagopus lagopus) camouflaged on autumn tundra