The many stands of aspen trees attract woodpeckers, whose habit of hollowing out rotted sections in turn attract the house wren, saw-whet owl, chickadees and swallows looking for nesting places. The flatlands in the valleys provide homes to sage grouse, vesper sparrows and sage thrashers. The alpine region above the 10,000-foot mark in the mountains is where such species as golden eagles, rosy finches, water pipits and the Clark's nutcracker exist. The Grand Teton National Park has many bodies of water that waterfowl like the common merganser, loon, heron and cormorant look for fish. Raptors such as the osprey and bald eagle patrol the skies here as well. North America's largest bird, the trumpeter swan, mates in this environment.
Fish are an important part of the food chain in the Grand Tetons, providing meals for many mammals and birds and also gobbling up huge numbers of insects in the water themselves. The park is famous for its trout population and excellent fishing, with rainbow, brown, brook, lake and cutthroat trout in the lakes, streams and rivers. Only the cutthroat variety is a native species. Other native fish include the longnose dace, the Utah sucker, the redside shiner, the mountain whitefish, the speckled dace, the mountain sucker and the mottled sculpin. The bluehead sucker, arctic grayling and Utah chub are introduced species that have flourished in the park's bodies of water.
Four species of shrews and six species of bats are among the small mammals living in Grand Teton National Park. The pika, snowshoe hare and white-tailed jackrabbits are the species belonging to the rabbit and hare families in the region. Rodents make up a large chunk of the small mammal population, with chipmunks, mice, voles, squirrels, marmots and gophers in that number. The larger rodents include the beaver, muskrat and porcupine.
The predators are represented in the Grand Tetons with the grizzly bear and the black bear being the two largest in this part of the country. Occasional reports of the gray wolf and the red fox show that these animals sometimes range into the park. Sightings of lynx, bobcat and cougar are also rare. Martens, long-tailed weasels, otters and badgers are common while mink, wolverine and skunks are not. The hoofed mammals are among the most visible of the creatures in the Grand Teton National Park. These include the bison, elk, moose, pronghorn antelope and the mule deer. Visitors will infrequently spot a white-tailed deer, bighorn sheep or mountain goat, with the last two species living in the high peaks most of the year.