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
Vernal Falls at peak flow in late spring, with a rainbow appearing in the spray of the falls, viewed from the Mist Trail.
Location: Vernal Falls, Yosemite National Park, California
Image ID: 12634
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
Scalloped hammerhead shark swims over a reef in the Galapagos Islands. The hammerheads eyes and other sensor organs are placed far apart on its wide head to give the shark greater ability to sense the location of prey.
Species: Scalloped hammerhead shark, Sphyrna lewini
Location: Wolf Island, Galapagos Islands, Ecuador
Image ID: 16246
Townsley Lake (10396'), a beautiful alpine lake sitting below blue sky, clouds and Fletcher Peak (right), lies amid the Cathedral Range of glacier-sculpted granite peaks in Yosemite's high country, near Vogelsang High Sierra Camp.
Location: Yosemite National Park, California
Image ID: 23206
White southern right whale calf underwater, Eubalaena australis. About five per cent of southern right whales are born white due to a condition known as grey morphism and will gradually turn dark as they age. They are not albino (which is a complete lack of pigmentation). Sometimes referred to as "brindled", the white coloration is a recessive genetic trait and only lasts a few months. Typically, but not always, white calves will become much darker as they mature but will still be somewhat lighter than normal even as adults.
Species: Southern Right Whale, Eubalaena australis
Location: Puerto Piramides, Chubut, Argentina
Image ID: 35908
Mother and calf southern right whales underwater. The calf swims close to its mother but, if the mother is accepting, the calf will be allowed to come close to the photographer and check him out.
Species: Southern Right Whale, Eubalaena australis
Location: Puerto Piramides, Chubut, Argentina
Image ID: 38309
Mother and calf southern right whales underwater. The calf swims close to its mother but, if the mother is accepting, the calf will be allowed to come close to the photographer and check him out.
Species: Southern Right Whale, Eubalaena australis
Location: Puerto Piramides, Chubut, Argentina
Image ID: 38303
Mother and calf southern right whales underwater. The calf swims close to its mother but, if the mother is accepting, the calf will be allowed to come close to the photographer and check him out.
Species: Southern Right Whale, Eubalaena australis
Location: Puerto Piramides, Chubut, Argentina
Image ID: 38313