This opening image is far different from a photograph I made of the same arch on a previous visit to Yellowstone in the late fall of 2008. The image I made then ( http://www.pbase.com/image/104717209 ) speaks of chilling cold, while this image, made from a far different perspective, speaks of the coming of spring. The snows of winter still linger on the mountains in the background, yet the giant swirl of cloud seems about to bring a nourishing shower to the fields of green below it. This historic northern gateway to Yellowstone, was built in the early 20th century, and dedicated by President Theodore Roosevelt himself.

I photographed our national bird perched high on a dead tree on the banks of the Madison River. Being clear of spring foliage, the tree offers an undisturbed vantage point to the eagle, which waits patiently for signs of passing fish.

This was one of four female bighorns that we found foraging in Yellowstone’s Lamar Valley, which in the spring is known as “America’s Serengeti.” Within eyesight at the time were not only these bighorns, a rare sight at such close range, but also bison, pronghorn, and elk. Meanwhile, just down the road, two black bears grazed in a field. I made numerous images of these bighorn sheep as they worked their way down a slope towards us. This was the shot I was waiting for – it represents the instant one of them dared to cross the diagonal highway boundary separating the world of nature from the world of man.

Mammoth Hot Springs brings tourists within a few feet of springs of boiling water, warmed by the magmatic heat pouring from the earth’s interior. These people stand amidst the steam on the boardwalk at Canary Springs.

Moving from the deep blues of Excelsior Geyser Crater, we found these rich yellows in Orange Spring Mound, near Mammoth Hot springs, a natural color which perhaps played a role in the naming of Yellowstone National Park. Made of travertine (calcium carbonate), such formations as these are often rich in primary colors.

This image begins a sequence on the bison, also known as the American buffalo. I found this one fording the Firehole River, given its name by the hot springs that line its path. Yellowstone has the largest free roaming bison population in the world. The herd numbers 3,500.