Forged by the volcanic heat that still bubbles at the heart of this great American wilderness, the mighty Yellowstone was the first of America’s National Parks. Located mostly in Wyoming, it is a place where bison roam free and the gray wolf has returned, re-establishing the natural order of the ecosystem.

Food is scarce during the harsh winter months, and the battle to survive is intense. The successful wolf pack hunts constantly to feed each hungry mouth, and the weary bison must dig through layers of snow if they are to feed at all.

Creatures large and small, from the bison to the ephydrid fly, make use of hot springs to survive the coldest winter months. Others, like the bears, hibernate, emerging ravenous when the weather finally warms, and ready to scrap for whatever food they can find.

Warm sunshine melts the last of the winter snow, and in the valleys of Yellowstone, animal mothers give birth to their young, bringing them into a beautiful yet perilous world.

Yellowstone is home to a small cougar population, but theyare rare and seldom seen. The noisy ruffed grouse or “thunder chicken” is far less elusive, as the males “drum” their wings loudly in the breeding season, advertising their presence to any nearby female birds.

As soon as it can stand, a young bison calf follows its mother and the herd, even through rivers of ice cold melt water. Meanwhile, the carcass of a bison that did not survive is fought over by wolves and grizzly bears.

A young bison calf is swept away by the icy torrent as the herd crosses a river. Against the odds, it washes up on a small island, but with night approaching, and its mother nowhere in sight, the outlook seems bleak for this little one.

Without its pack, a wolf is a far lesser threat, and the other animals know it. However, for the lost bison calf, trapped on a small island, a lone wolf is a mortal danger, one that would take a minor miracle to survive.

Color and new life returns to Yellowstone as summer returns, and the animals race to make the most of this window of warm weather, which they know will be as brief as it is bright.

This is a landscape in constant flux, with a live supervolcano simmering beneath the surface. But for the young animals, there is now time to relax and enjoy the warmth and tranquility of the late summer. As they move towards maturity, a mellow sunlight shines on peaceful scenes in Yellowstone National Park.

The height of summer brings striking rainbow colors to one of Yellowstone’s hot springs. This is also the peak of the bison rut, when the park’s muscular bulls challenge one another for the opportunity to mate.

Autumn arrives, and the bison rut draws to an end. For many animals, this is a time of quiet preparations. They are getting ready for the hardships of another winter as the cycle of the seasons continues.