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.

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.

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.

Sigrid finishes preparing her simple lunch using the wild greens she had gathered that morning.

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.

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.

Back home, Sigrid works out on her terrace preparing the greens she has picked. She will cook the lambsquarters, but she'll eat the purslane raw, as a salad. She also has some regrets about one missed opportunity.

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.

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.

With the winter drawing in, the animals prepare once more for that harshest of seasons within the breathtaking confines of the world’s greatest gorge, the Grand Canyon National Park.

A fearsome American badger is on the hunt, and the prairie dogs are not even safe in their burrows. The north rim of the canyon thunders with rutting bison, as the big males lock horns to establish superiority.

Pronghorns are extremely fast and can easily outrun a mountain lion! Even so, they must watch where they tread as the canyon floor is littered with holes... prairie dogs live here and may share their burrows with some unusual birds that nest underground.

The rare California condor has been successfully re-introduced in the Grand Canyon, and scientists monitor their progress by tagging the individual birds to identify them. As scavengers, they feed on the carcasses of dead animals, but are actually very clean creatures.

People have traveled through the canyon for millennia, and some even made this place their home. However, in the extreme weather of the monsoon season, this is a perilous and inhospitable environment for all but the best adapted native wildlife.

In Central Park, John finds himself next to a sculpture of the Danish writer Hans Christian Andersen, author of some of the world’s best loved stories, including "The Ugly Duckling."