Thomas Mangelsen / Gray Wolf (Canis lupus) surveying the tundra, Denali National Park, Alaska

Thomas Mangelsen / King Penguin (Aptenodytes patagonicus) group of downy chicks, Fortuna Bay, South Georgia

Thomas Mangelsen / Grizzly Bear (Ursus arctos horribilis) in autumn tundra landscape, Denali National Park and Preserve, Alaska

Thomas Mangelsen / African Lion (Panthera leo), Ngorongoro Crater, Tanzania

Thomas Mangelsen / African Lion (Panthera leo) male portrait, Masai Mara, Kenya

Thomas Mangelsen / African Elephant (Loxodonta africana) matriarch and family, Amboseli National Park, Kenya

Thomas Mangelsen / African Lion (Panthera leo) male portrait, Masai Mara National Reserve, Kenya

Thomas Mangelsen / Blue Wildebeest (Connochaetes taurinus) and newborn, Kenya

Thomas Mangelsen / Bald Eagle (Haliaeetus leucocephalus) flying with captured fish in talons, Homer, Alaska

Thomas Mangelsen / Sunset over Antler Creek, Yellowstone National Park, Wyoming

Thomas Mangelsen / White Ibis (Eudocimus albus) trio feeding at sunset, Ding Darling National Wildlife Refuge, Sanibel Island, Florida

Thomas Mangelsen / Polar Bear (Ursus maritimus) walking on ice at sunset, Churchill, Manitoba, Canada