Male elk bugling during the fall rut. Large male elk are known as bulls. Male elk have large antlers which are shed each year. Male elk engage in competitive mating behaviors during the rut, including posturing, antler wrestling and bugling, a loud series of screams which is intended to establish dominance over other males and attract females.
Species: Elk, Cervus canadensis
Location: Mammoth Hot Springs, Yellowstone National Park, Wyoming
Image ID: 19693
A rainbow appears in the mist of the Lower Falls of the Yellowstone River. At 308 feet, the Lower Falls of the Yellowstone River is the tallest fall in the park. This view is from Lookout Point on the North side of the Grand Canyon of the Yellowstone. When conditions are perfect in midsummer, a midmorning rainbow briefly appears in the falls.
Location: Grand Canyon of the Yellowstone, Yellowstone National Park, Wyoming
Image ID: 13319
Grand Prismatic Spring (left) and Excelsior Geyser (right). Grand Prismatic Spring displays a stunning rainbow of colors created by species of thermophilac (heat-loving) bacteria that thrive in narrow temperature ranges. The blue water in the center is too hot to support any bacterial life, while the outer orange rings are the coolest water. Grand Prismatic Spring is the largest spring in the United States and the third-largest in the world. Midway Geyser Basin.
Location: Midway Geyser Basin, Yellowstone National Park, Wyoming
Image ID: 13571
Old Faithful geyser, sunrise. Reaching up to 185' in height and lasting up to 5 minutes, Old Faithful geyser is the most famous geyser in the world and the first geyser in Yellowstone to be named.
Location: Upper Geyser Basin, Yellowstone National Park, Wyoming
Image ID: 26939
A brown pelican preening, uropygial gland (preen gland) visible near the base of its tail. Preen oil from the uropygial gland is spread by the pelican's beak and back of its head to all other feathers on the pelican, helping to keep them water resistant and dry. Note adult winter breeding plumage in display, with brown neck, red gular throat pouch and yellow and white head. This adult is just transitioning to the brown hind neck that characterizes breeding brown pelicans.
Species: Brown Pelican, Pelecanus occidentalis, Pelecanus occidentalis californicus
Location: La Jolla, California
Image ID: 36682
The bisons massive head is its most characteristic feature. Its forehead bulges because of its convex-shaped frontal bone. Its shoulder hump, dwindling bowlike to the haunches, is supported by unusually long spinal vertebrae. Over powerful neck and shoulder muscles grows a great shaggy coat of curly brown fur, and over the head, like an immense hood, grows a shock of black hair. Its forequarters are higher and much heavier than its haunches. A mature bull stands about 6 1/2 feet (2 meters) at the shoulder and weighs more than 2,000 pounds (900 kilograms). The bisons horns are short and black. In the male they are thick at the base and taper abruptly to sharp points as they curve outward and upward; the females horns are more slender.
Species: American bison, Bison bison
Location: Yellowstone National Park, Wyoming
Image ID: 13120