Forty-five years of the US Wilderness Act

Grand prize winner: Yellowstone national park, Wyoming, by William Hacker Photograph: William Hacker/The Wilderness Society

Second place: Eagle at Aniakchak Bay in the Aniakchak national monument and preserve, Alaska, by Buzz Hoffman Photograph: Buzz Hoffman/The Wilderness Society

Third place: Ramona Falls in Mt Hood wilderness, Oregon, by Eli Boschetto Photograph: Eli Boschetto/The Wilderness Society

Fourth place: Spring gales in Mini-Wakan state park, Iowa, by ruf_d Photograph: ruf_d/The Wilderness Society

Fifth place: Sunrise from Tennent mountain summit in the Shining Rock wilderness, North Carolina, by mherring Photograph: mherring/The Wilderness Society

Bison making their way across a flooded meadow in Yellowstone national park, Wyoming, by Scorpions and Centaurs Photograph: Scorpions and Centaurs/The Wilderness Society

A blue heron with small fish, Florida, by starpower2001 Photograph: starpower2001/The Wilderness Society

Canada geese in a snowstorm over Hottes Lake, Iowa, by ruf_d Photograph: ruf_d/The Wilderness Society

Crab in Cape Cod, Massachusetts, by deel34 Photograph: deel34/The Wilderness Society

Grand Canyon national park, Arizona, by Jason K. Bach Photograph: Jason K. Bach/The Wilderness Society

Great horned owl and chick, by eileenfonerko Photograph: eileenfonerko/The Wilderness Society

Great Sand Dunes national park and preserve, Colorado, by tchiakulas Photograph: tchiakulas/The Wilderness Society

Mt Denali in Alaska by hawghead56 Photograph: hawghead56/The Wilderness Society

Redwood national park, California, by sharloch Photograph: sharloch/The Wilderness Society

Sylvania wilderness area, Michigan, by Jeff Rennicke Photograph: The Wilderness Society

The Narrows in Zion national park, Utah, by fbs1975 Photograph: fbs1975/The Wilderness Society

Ducks at Itasca state park, Minnesota, the headwaters of the Mississippi River by ruf_d Photograph: ruf_d/The Wilderness Society

Strawberry hedgehog cactus in Ironwood forest national monument, Arizona, by Murray Bolesta Photograph: Murray Bolesta/The Wilderness Society

Wild bull moose at Lake Isabella, Colorado, by Jason K. Bach Photograph: Jason K. Bach/The Wilderness Society