Yellowstone National Park, renowned for its spectacular geysers, hot springs, and dramatic landscapes, is equally celebrated for its incredible diversity of wildlife. Encompassing over 2.2 million acres of protected wilderness, the park provides a sanctuary for countless species of mammals, birds, fish, reptiles, amphibians, and invertebrates. Its role within the Greater Yellowstone Ecosystem, one of the largest nearly intact temperate-zone ecosystems on Earth, makes it a critical refuge for animals that have vanished from much of their historic habitats. Observing Yellowstone’s wildlife offers visitors a glimpse into the balance of nature, predator-prey relationships, and the resilience of species in a protected environment.
Table of Contents
Quick Reference Table: Animals in Yellowstone National Park
| Species | Category | Key Details |
|---|---|---|
| American Bison | Mammals | Largest land mammal in North America; bulls up to 2,000 lbs; found in herds across park; iconic symbol |
| Elk | Mammals | Large cervid; bulls 700–1,100 lbs; prominent antlers; seasonal rut; grazer of grasses and shrubs |
| Bighorn Sheep | Mammals | Rocky slopes specialist; rams 150–300 lbs; curved horns; agile climber |
| Moose | Mammals | Largest deer family member; bulls up to 1,500 lbs; wetlands and riparian zones; solitary; palmate antlers |
| Mountain Goat | Mammals | Introduced species; steep cliffs; males 150–300 lbs; thick white fur; skilled climber |
| Mule Deer | Mammals | Common throughout park; bucks 150–300 lbs; forked antlers; adaptable grazer |
| Pronghorn Antelope | Mammals | Fastest North American land mammal; 120–150 lbs; open grasslands; forked horns |
| White-tailed Deer | Mammals | Lower elevation forests; bucks 150–300 lbs; single-beam antlers; agile escapees |
| Grizzly Bear | Mammals | Apex omnivore; males 400–600 lbs; shoulder hump; varied diet; critical predator |
| Black Bear | Mammals | Smaller omnivore; males 150–300 lbs; forests and meadows; opportunistic diet |
| Gray Wolf | Mammals | Keystone predator; packs 4–8; prey on elk, bison; 70–110 lbs; restored ecosystem balance |
| Wolverine | Mammals | Solitary carnivore; 20–40 lbs; alpine habitats; scavenger and predator |
| Coyote | Mammals | Widespread omnivore; 24–46 lbs; versatile diet; controls rodent populations |
| Mountain Lion | Mammals | Solitary apex predator; males 120–200 lbs; ambush hunter of deer and elk |
| Canada Lynx | Mammals | Rare forest predator; 15–30 lbs; tufted ears; specializes on snowshoe hare |
| Red Fox | Mammals | Adaptable canid; 6–24 lbs; omnivorous; forests and meadows |
| River Otter | Mammals | Semi-aquatic; 10–30 lbs; rivers and lakes; feeds on fish and crustaceans |
| American Marten | Mammals | Forest carnivore; 1.5–3.5 lbs; arboreal; small mammals diet |
| American Pika | Mammals | Small alpine herbivore; 6–9 oz; collects vegetation for winter; rocky slopes |
| North American Porcupine | Mammals | Rodent with quills; 10–30 lbs; arboreal; feeds on leaves, bark, twigs |
| Bald Eagle | Birds | Raptor; hunts fish; nests near rivers and lakes; large wingspan |
| Golden Eagle | Birds | Raptor; hunts mammals and birds; soars over open terrain |
| Osprey | Birds | Fish specialist; dives to catch prey; nests along waterways |
| Peregrine Falcon | Birds | Fastest bird; cliff nester; preys on smaller birds |
| Red-tailed Hawk | Birds | Common raptor; hunts rodents in meadows and grasslands |
| Great Horned Owl | Birds | Nocturnal predator; hunts mammals and birds; forest and open areas |
| Barn Owl | Birds | Nocturnal; hunts rodents; silent flight; fields and meadows |
| Mountain Bluebird | Birds | Songbird; insectivore and seed eater; open habitats |
| Yellow-rumped Warbler | Birds | Songbird; forest edges; feeds on insects and berries |
| Western Tanager | Birds | Songbird; colorful; eats insects and fruits; forested areas |
| Killdeer | Birds | Shorebird; muddy shores; feeds on insects and invertebrates |
| Sandhill Crane | Birds | Wetlands and meadows; omnivorous; migratory |
| Common Loon | Birds | Aquatic bird; fish-eating; lakes and large water bodies |
| Trumpeter Swan | Birds | Largest North American waterfowl; wetlands and rivers; conservation success |
| Yellowstone Cutthroat Trout | Fish | Native; feeds predators; streams and lakes |
| Westslope Cutthroat Trout | Fish | Native; cold, clear streams; vital for bears and eagles |
| Arctic Grayling | Fish | Native; small streams; sensitive to habitat changes |
| Mountain Whitefish | Fish | Native; streams and rivers; omnivorous diet |
| Lake Trout | Fish | Non-native; deep lakes; competes with native trout |
| Rainbow Trout | Fish | Non-native; recreational fishing; competes with natives |
| Brown Trout | Fish | Non-native; rivers and lakes; predator of smaller fish |
| Prairie Rattlesnake | Reptiles | Venomous; grasslands; predator of small mammals |
| Bullsnake | Reptiles | Non-venomous; open habitats; rodent control |
| Rubber Boa | Reptiles | Rare; forested zones; secretive; small mammals diet |
| Garter Snake | Reptiles | Common; streams and wetlands; eats amphibians and fish |
| Sagebrush Lizard | Reptiles | Only lizard in Yellowstone; dry, rocky habitats |
| Western Tiger Salamander | Amphibians | Wetlands and ponds; carnivorous larvae; adult insectivore |
| Boreal Chorus Frog | Amphibians | Small frog; wetlands; insectivorous |
| Western Toad | Amphibians | Amphibian; streams and forest floors; insectivore |
| Columbia Spotted Frog | Amphibians | Wetlands; predator of insects; indicator of habitat health |
| Plains Spadefoot Toad | Amphibians | Burrowing amphibian; ephemeral ponds; insectivorous |
Mammals in Yellowstone National Park
Mammals form a cornerstone of Yellowstone’s biodiversity, ranging from enormous herbivores like bison and elk to elusive carnivores such as wolves and wolverines. The park is home to 67 mammal species, including eight ungulates and seven large predators, providing a rich predator-prey dynamic that is essential to the ecosystem. Yellowstone’s mammal populations are globally significant due to their size, diversity, and historical continuity in North America.
American Bison
The American bison is perhaps the most iconic mammal in Yellowstone. These massive creatures are the largest land animals in North America and have thrived in the park continuously since prehistoric times. Yellowstone hosts one of the continent’s largest wild bison herds, estimated at around 5,000 individuals. Bulls can weigh up to 2,000 pounds and stand about six feet tall at the shoulder, while cows are roughly half that size. Despite their size, bison are remarkably agile, capable of running 35 miles per hour and swimming across rivers to reach grazing grounds. They hold cultural significance for many Native American tribes, serving as symbols of sustenance, spirituality, and resilience. Visitors are encouraged to admire bison from a safe distance of at least 25 yards to avoid danger, as these wild animals are unpredictable.
Elk
Elk, also called wapiti, are another emblematic species of Yellowstone. These majestic animals are among the largest cervids in North America, with bulls weighing between 700 and 1,100 pounds and cows between 500 and 600 pounds. Yellowstone supports several large elk herds, particularly in the Northern Range, with seasonal migrations bringing them to different parts of the park. The rut, when bulls compete for mates, is a spectacular event marked by bugling calls and dramatic displays of antlers. Elk feed primarily on grasses, shrubs, and young trees, and their grazing patterns significantly influence plant communities across the park.
Bighorn Sheep
Bighorn sheep are well-known for their large, curved horns and exceptional climbing abilities. These agile animals are primarily found in Yellowstone’s steep, rocky areas such as Mount Washburn and the Gardner River Canyon. Adult rams weigh between 150 and 300 pounds, while ewes are smaller, weighing between 75 and 200 pounds. The horns of rams can grow throughout their lives, sometimes weighing as much as 30 pounds. Bighorn sheep live in small social groups, with rams forming bachelor groups outside the breeding season. Their sure-footedness allows them to navigate terrain inaccessible to most predators, making them uniquely adapted to the park’s rugged landscapes.
Moose
Moose are the largest members of the deer family and a striking presence in Yellowstone’s wetlands and riparian zones. Adult bulls can reach heights of up to seven feet at the shoulder and weigh between 1,200 and 1,500 pounds, while cows are slightly smaller. Moose are primarily solitary and favor marshes, lakeshores, and river valleys where they can browse on aquatic plants, willows, and shrubs. Their broad, palmate antlers, which can span six feet, are shed annually. Yellowstone’s moose populations are relatively small, making sightings a special treat for visitors, particularly in areas like Lamar Valley and Bechler River.
Mountain Goats
Mountain goats are high-altitude specialists introduced to Yellowstone in the 1960s. They inhabit the park’s northern ranges, including the Absaroka Mountains, and thrive on steep, rocky cliffs where they can evade predators. Adult males weigh between 150 and 300 pounds, while females are slightly smaller. Both sexes have thick, white fur and curved horns that aid in defense and climbing. Mountain goats are known for their agility, capable of navigating precipitous terrain with ease. Although not native, they have become an established part of the park’s wildlife and attract considerable attention from hikers and wildlife enthusiasts.
Mule Deer
Mule deer are among Yellowstone’s most commonly observed ungulates. Named for their large ears, these deer inhabit forests, meadows, and river valleys throughout the park. Adult bucks typically weigh between 150 and 300 pounds, while does are smaller, weighing between 100 and 150 pounds. Their antlers are forked, growing larger each year. Mule deer’s adaptability to different habitats and their keen senses make them successful grazers, although they must remain vigilant against predators such as wolves and mountain lions. They are particularly abundant in areas like Lamar Valley and Hayden Valley, where open landscapes provide both grazing opportunities and clear lines of sight for predator detection.
Pronghorn Antelope
Pronghorns are North America’s fastest land mammals, capable of reaching speeds up to 55 miles per hour. They are unique, as the only surviving members of the family Antilocapridae, and are typically found in Yellowstone’s open grasslands and sagebrush flats. Adult males weigh 120 to 150 pounds, while females are slightly lighter. Their slender bodies, long legs, and distinctive forked horns enable them to evade predators efficiently. Pronghorns are an iconic species of the Northern Range, particularly around the Lamar Valley, where their presence underscores the importance of wide-open habitats for their survival.
White-tailed Deer
White-tailed deer are less common in Yellowstone compared to mule deer, preferring lower elevations and areas with dense vegetation. They are named for the prominent white underside of their tail, which they raise to signal danger. Adult bucks weigh 150 to 300 pounds, with females slightly smaller. Unlike mule deer, their antlers grow along a single beam with branching tines. These deer are highly agile, capable of rapid changes in direction to escape predators. Although elusive, they occupy a critical ecological niche, providing prey for large carnivores and contributing to the park’s herbivore diversity.
Grizzly Bears
Grizzly bears are apex omnivores and one of Yellowstone’s most recognizable predators. With a population of roughly 1,063 in the Greater Yellowstone Ecosystem, they occupy forests, meadows, and river valleys. Adult males typically weigh 400 to 600 pounds, and females 250 to 400 pounds. Grizzlies are distinguished by a pronounced shoulder hump and strong claws up to four inches long, enabling them to dig for roots, insects, and small mammals. Their diet is varied, including berries, nuts, fish, and carrion, and they play a vital role in shaping the park’s ecosystems. Grizzly bears were once listed as threatened but have recovered significantly through conservation efforts.
Black Bears
Black bears are smaller than grizzlies but are more common and adaptable, thriving in forests, meadows, and riparian zones across Yellowstone. Adult males range from 150 to 300 pounds, while females typically weigh 100 to 200 pounds. Black bears are omnivorous, consuming fruits, nuts, insects, small mammals, and occasionally fish. Unlike grizzlies, they lack a prominent shoulder hump and exhibit a more uniform body shape. Black bears are highly adaptable, capable of foraging in diverse habitats, and are frequently observed by park visitors.
Gray Wolves
Gray wolves are a keystone species in Yellowstone, with their reintroduction in 1995 marking a major conservation success. Packs usually consist of four to eight members, including an alpha pair and their offspring. Wolves primarily prey on large ungulates such as elk and bison, regulating herbivore populations and preventing overgrazing. Adults weigh between 70 and 110 pounds and display coat colors ranging from white and gray to black and brown. Wolves are social, intelligent hunters whose presence has restored balance to Yellowstone’s ecosystem and even influenced river and vegetation patterns through their effects on prey behavior.
Wolverines
Wolverines are solitary, elusive predators inhabiting Yellowstone’s high elevations. As the largest members of the weasel family, they weigh 20 to 40 pounds and are equipped with strong jaws and claws for scavenging and hunting small prey. Wolverines have vast territories and are well adapted to cold climates, caching food to survive scarce winter months. Their rarity makes sightings extremely uncommon, highlighting the importance of remote, protected habitats for their persistence.
Coyotes
Coyotes are versatile and widespread throughout Yellowstone, occupying meadows, forests, and river valleys. Adult coyotes weigh 24 to 46 pounds and have slender bodies with long legs and bushy tails. Omnivorous and opportunistic, they feed on small mammals, birds, insects, fruits, and carrion. Coyotes’ adaptability allows them to thrive in a variety of ecosystems, and they play a key role in controlling rodent populations and maintaining ecological balance in the park.
Mountain Lions
Mountain lions, also called cougars, are solitary apex predators that primarily inhabit Yellowstone’s rugged terrain. Adult males weigh 120 to 200 pounds, while females weigh 65 to 100 pounds. They prey mainly on deer and elk, using stealth and strength to ambush their targets. Mountain lions are primarily nocturnal and crepuscular, making sightings rare. Their elusive nature and solitary behavior highlight the importance of expansive habitats for large carnivores.
Canada Lynx
Canada lynx are rare forest-dwelling predators found in higher elevations of Yellowstone. Adult lynx weigh 15 to 30 pounds and have distinctive tufted ears, short tails, and large, padded paws adapted for walking on snow. Their diet primarily consists of snowshoe hares, but they may hunt other small mammals when necessary. Lynx are highly elusive, and their presence is often detected through tracks or scat rather than direct sightings.
Red Foxes
Red foxes are adaptable canids inhabiting forests, meadows, and park edges. Weighing 6 to 24 pounds, they have a reddish-orange coat with black markings on their legs, ears, and tail tip. Red foxes are primarily nocturnal and omnivorous, feeding on small mammals, birds, insects, fruits, and carrion. They are highly intelligent, skilled hunters that cache food for future use, and their vocalizations include barks and howls used for communication.
River Otters
River otters are playful semi-aquatic mammals that inhabit Yellowstone’s rivers, lakes, and wetlands. Weighing 10 to 30 pounds, they have streamlined bodies, webbed feet, and dense waterproof fur. Otters primarily feed on fish but also consume amphibians, crustaceans, and small mammals. They are social animals and are often seen sliding on mud or snowbanks, swimming, or engaging in playful interactions, making them a favorite among wildlife watchers.
American Martens
American martens are elusive forest carnivores inhabiting mature coniferous forests. Weighing 1.5 to 3.5 pounds, they are agile climbers with thick fur and bushy tails. Martens feed mainly on small mammals, birds, and insects and are highly territorial. Their presence indicates healthy forest ecosystems, and their arboreal behavior makes them challenging to observe.
American Pikas
American pikas are small herbivorous mammals that inhabit rocky slopes and alpine meadows. They weigh 6 to 9 ounces and are adapted to cold, high-altitude environments. Pikas are diurnal and known for collecting “haypiles” of vegetation to sustain them through harsh winters. Their vocalizations and territorial behavior are distinctive, making them an intriguing component of Yellowstone’s alpine wildlife.
North American Porcupines
Porcupines are medium-sized rodents with a coat of sharp quills for defense. They weigh 10 to 30 pounds and spend much of their time in trees foraging and shelter. Primarily herbivorous, they feed on leaves, twigs, and bark. Their quills provide an effective deterrent against predators, and porcupines are a fascinating example of adaptation in Yellowstone’s forests.
Birds in Yellowstone National Park
Yellowstone is home to over 300 bird species, ranging from powerful raptors to tiny songbirds. Birds inhabit every niche of the park, from rivers and lakes to forests, meadows, and wetlands.
Raptors
Raptors, such as Bald Eagles, Golden Eagles, and Ospreys, dominate the skies. Bald Eagles are frequently seen hunting fish near rivers and lakes, while Golden Eagles soar over open terrain in search of prey. Ospreys nest along waterways and dive dramatically to catch fish. Peregrine Falcons, the fastest birds in the world, nest on cliffs and feed on smaller birds. Northern Harriers and hawks, including Red-tailed and Swainson’s Hawks, patrol grasslands for rodents and other small prey.
Owls
Owls are powerful nocturnal hunters that play a vital role in controlling rodent populations. Great Horned Owls, known for their deep hoots, hunt in forests and open areas. Barn Owls hunt silently in open fields, while Northern Saw-whet and Long-eared Owls occupy forested regions. Owls’ keen senses and stealthy hunting make them key nocturnal predators.
Songbirds
Songbirds, including Mountain Bluebirds, Yellow-rumped Warblers, and Western Tanagers, add vibrant color and melody to Yellowstone. Sparrows, such as Song Sparrows and Chipping Sparrows, and House Wrens are widespread. These birds are vital for pollination and insect control, and their presence enhances the park’s ecological diversity.
Shorebirds
Shorebirds inhabit Yellowstone’s wetlands and lake edges. Killdeer, Greater and Lesser Yellowlegs, Spotted Sandpipers, and Wilson’s Snipe forage along muddy shores and shallow waters. These birds are important indicators of wetland health and contribute to the park’s biodiversity.
Waterfowl
Waterfowl are abundant in Yellowstone’s rivers and lakes. Species include Mallards, Northern Pintails, American Black Ducks, Common Goldeneyes, Canada Geese, and Common Mergansers. The Trumpeter Swan, the largest native waterfowl in North America, thrives in the park and serves as a symbol of successful conservation efforts.
Other Notable Birds
Other remarkable birds include Common Loons, Double-crested Cormorants, American White Pelicans, American Dippers, and Ravens. Sandhill Cranes, Rock Wrens, Clark’s Nutcrackers, Black-capped Chickadees, and the rare White-headed Woodpecker further enrich Yellowstone’s avian community.
Fish in Yellowstone National Park
Yellowstone’s waters host both native and non-native fish species, which are critical to aquatic ecosystems and terrestrial predators.
Native Fish
Native species, such as Yellowstone Cutthroat Trout, Westslope Cutthroat Trout, and Arctic Grayling, provide food for grizzly bears, eagles, and other wildlife. Other natives include Mountain Whitefish, Rocky Mountain Sculpin, Utah Chub, Redside Shiner, Longnose Dace, Speckled Dace, Mountain Sucker, Longnose Sucker, and Utah Sucker. These species are integral to the park’s ecological balance.
Non-native Fish
Non-native fish, including Lake Trout, Rainbow Trout, Eastern Brook Trout, Brown Trout, Lake Chub, and hybrid Cutthroat x Rainbow Trout, have been introduced to Yellowstone’s waters. Lake Trout, in particular, have had devastating effects on native Yellowstone Cutthroat Trout populations, altering predator-prey dynamics and affecting the broader ecosystem.
Reptiles in Yellowstone National Park
Reptiles, though less diverse, contribute to the park’s ecological balance. Bullsnakes and Prairie Rattlesnakes inhabit grasslands and rocky areas, while the rare Rubber Boa lives in secluded forested zones. Garter snakes, including Common and Terrestrial species, are widespread near streams and wetlands. The Sagebrush Lizard is Yellowstone’s only lizard species, thriving in dry, rocky habitats.
Amphibians in Yellowstone National Park
Amphibians are sensitive indicators of environmental health in Yellowstone. Species include the Western Tiger Salamander, Boreal Chorus Frog, Western Toad, Columbia Spotted Frog, and Plains Spadefoot Toad. These species inhabit wetlands, streams, and moist forest floors and play a vital role in controlling insect populations and contributing to nutrient cycling.