National Park’s most iconic wolves were killed outside the park when the species was temporarily delisted in Wyoming between 2012 and 2014.
Outside of sunny winter days, the best times to spot wolves are at dawn and dusk. The most reliable method of finding them? Scan roadside turn-outs for an array of high-powered binoculars and spotting scopes, telephoto lenses mounted on camouflage tripods, and CB radio antennas on the roofs of expedition-equipped four-wheel-drive vehicles. Then stop and ask if you can take a look; devoted wolf-watchers are usually quite happy to share their knowledge and passion with passersby.
The highly adaptable, omnivorous coyote is often seen loping across meadows, fields, and other open grasslands. The coyote population has decreased by as much as 50% in Yellowstone since wolf reintroduction, which has been shown conclusively to have relegated coyotes to a scavenger role. However, the nighttime chorus of yelps (sometimes mistaken for wolf howls) still reverberates through backcountry campsites.
Stay clear of bull bison like this fellow in Pelican Valley (Trail 23)
Estimates of the numbers of the seven species of native ungulates vary as widely as the large animals’ migratory range. Counts of Yellowstone’s bugling Rocky Mountain elk (also known as wapiti) vary seasonally from 10,000 to 20,000 in summer to 5,000 in winter, in seven distinct herds. Over 100,000 elk inhabit Greater Yellowstone. In summer, you can hardly toss a bison chip without hitting a member of the largest elk herd in North America: look around Gibbon Meadows or the Lamar Valley. During the autumn rut (mating season), elk take over the lawns around Mammoth Hot Springs and flock to meadows around Norris Geyser Basin. In Jackson Hole, Timbered Island becomes a no-go zone during the rut. In winter, they migrate south to the National Elk Refuge, or north and east to Gardiner and West Yellowstone, where hunters await just beyond the park boundaries.
Yellowstone’s population of persistent bison (often used interchangeably with buffalo), the largest land animal in North America, is estimated at between 2,300 and 5,000. Watch year-round for what remains of the United States’ largest free-roaming herd in the Hayden and Lamar Valleys, in summer in open meadows and grasslands, and in winter in thermal areas and along the Madison River. In Grand Teton, smaller herds roam the sagelands around Mormon Row. In 2016, President Obama signed legislation designating the bison as the national mammal of the United States.
Common, floppy-eared mule deer prefer open forests and grassy meadows, where they munch on leaves, shrubs, and sedges. Watch for them browsing around dusk near forest edges. The furtive, less common white-tailed deer is only occasionally spotted near waterways in Yellowstone’s Northern Range.
A declining population of moody, drooling moose lurk in willow thickets in riparian zones, mainly in marshy meadows, near lakeshores, and along rivers. In Yellowstone, they are most frequently seen browsing in the Bechler region and in the Soda Butte Creek, Pelican Creek, Lewis River, and Gallatin River drainages. They are more common in Grand Teton, wherever willows colonize marshes and ponds. Appearances are deceptive: they are superb swimmers and can—and will—charge at up to 35 miles per hour, so give them wide berth.
A population of 350–400 fleet-footed pronghorn are more closely related to goats and are not true antelopes. They are found in summer in sage flats and grasslands in the Lamar Valley, in Jackson Hole, and near Yellowstone’s North Entrance. Their numbers declined by 50% in Yellowstone between 1991 and 1995; for context, the pre-European American settlement population is estimated at 35 million. The population has since stabilized, but large-scale energy developments outside Grand Teton jeopardize their long-distance winter migration routes around the park.
Numbering up to 300, Rocky Mountain bighorn sheep are often spotted scampering along cliffs and roaming Yellowstone’s alpine meadows. In summer, they are most easily found on the slopes of Mount Washburn, and yearround in Gardner Canyon between Mammoth and the North Entrance. Also watch for their silhouettes on cliff tops along the Yellowstone River, and above Soda Butte in the Lamar Valley.
Invasive, nonnative mountain goats are increasingly common and thought to be colonizing rocky slopes in Yellowstone’s northern reaches.
The population of the seldom-seen American cougar (also known as the mountain lion) is estimated at 26–42, making it Yellowstone’s most common cat species. Primarily nocturnal, cougars have been called “the ghosts of the Rockies.”
The similarly nocturnal and reclusive bobcat is poorly studied but thought to be widespread. You’re more likely to hear its bloodcurdling scream at night while snuggled inside your sleeping bag than to see it from the trail. Most reports are from the northern half of Yellowstone in sagebrush and conifer forests.
Other common small mammals include the wily, weasellike marten, found in coniferous forests; the playful river otter, found in rivers, lakes, and ponds; and two species of weasel (also known as ermine), widespread in both willows and spruce–fir forests. Beavers dam watercourses and cobble together lodges adjacent to trails in both parks.
Animals rarely seen by hikers include the sagebrush-loving badger and the red fox, found in the Lamar Valley and around Canyon Village at the edges of forest and sagelands. A recent three-year study confirmed the presence and reproduction of the wide-ranging Canadian lynx, which hides out in remote subalpine forests, on Yellowstone’s eastern flank. Other rare mammals include the relatively scarce raccoon; the carnivorous, forest-dwelling fisher; the weasel-like mink, occasionally seen in riparian forests; the striped skunk, seen flitting between the forest and riparian zones; and the fierce, elusive wolverine, the largest land member of the weasel family. Researchers live-trapped and released a wolverine in March 2006 just north of Yellowstone park—pretty impressive given the animal’s 350-to 500-mile range.
Three territorial species of chipmunk are common in conifer forests. Four squirrel species are common around rocky outcroppings in forests. The yellow-bellied marmot is commonly seen, or at least its high-pitched whistle is heard, where trails traverse rocky slopes. The bleating, round-eared pika is also common in this kind of landscape. Other rodents often spotted scurrying about the forest understory include gophers, mice, several species of voles, shrews, muskrats, bushy-tailed wood rats, and porcupines.
At last count, 322 bird species were winging around the skies above Greater Yellowstone, with 148 of those observed nesting. Early morning in spring (from mid-May through early July) is the best time for birding. While hiking around lakes and waterways, keep your eyes peeled for big raptors such as the threatened but recovering bald eagle and trout-loving osprey swooping around hunting for prey. Majestic but imperiled trumpeter swans range between Montana’s Paradise Valley and the Madison River. The reintroduced peregrine falcon, which preys on songbirds and waterfowl, nests in Yellowstone and is well on its way to recovery but is rarely seen.
Other common species that exhibit entertaining antics include the boisterous Clark’s nutcracker, the diminutive mountain chickadee, the mountain bluebird, and Steller’s jay, a bold scavenger. Other monitored species of special concern include the American white pelican, common loon, harlequin duck, osprey, colonial nesting bird, and great gray owl.
Yellowstone contains one of the most significant aquatic ecosystems in the United States. It’s home to 16 fish species: 11 native and 5 nonnative. Since 2001, regulations have required the release of all native sport fishes hooked in park waters. The fishing season runs from Memorial Day weekend through the first Sunday of November.
The three subspecies of native cutthroat trout are an essential but increasingly threatened source of grizzly sustenance. They are being eaten out of house and home by the proliferation of illegally introduced, nonnative lake trout, also known as mackinaws. Other native sport fish are the rare, protected Arctic grayling and the slender, silver mountain whitefish. Introduced
