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Wildlife in Yellowstone: Part One, Mammals

Yellowstone National Park is home to 67 species of #mammals, including everything from bear to montane vole, and from wolf to wolverine. The park contains the highest concentration of mammals in the contiguous United States.

The following list is in no means comprehensive, but provides details about some of the common mammals you may have a chance of seeing while in Yellowstone. Be sure to check out the Park Service's webpage about mammals in Yellowstone for more information.


#Bison: Yellowstone is home to the most important bison herd in the United States, for it is the country’s largest bison population on public land. It is also the only place in the United States that bison have continuously lived since prehistoric times.

As the largest land-dwelling animal in the United States, male bison can weigh up to one ton. They have a distinct hump on their shoulders, pure muscle, that allows them to swing their heavy head from one side to the other, in order to clear snow in the winter.

Mating season occurs in late-summer, and is characterized by male bison grumbling and groaning as they roam around looking for a mate. It is important to be especially cautious and aware when around male bison during mating season, that is 2,000 pounds of sexual aggression.

Bison calves are referred to as “red dogs” because of their amber color when they are born. Typically, bison calves are born in a short time period between April and May, this phenomenon is called “birth synchrony”.

Bison are most likely to be found in Lamar Valley and Hayden Valley.


#Elk: Yellowstone is home to 10,000 to 20,000 elk in the summer. Most elk migrate south to the Elk Refuge in the winter, leaving about 4,000 in Yellowstone in the winter.

Elk are most known for their antlers, larger racks having seven to eight points. Male elk begin growing antlers around one year of age. Antler growth is usually determined by decrease in testosterone levels and the lengthening of days. Male elk keep their antlers throughout the winter, and those with larger racks stay at the top of the herd’s social structure, giving them choice for mates and resources.

Elk mate in the fall, with the bull elk bugling (which is one of the most wild and wonderful noises) to attract female elk, called cows. They strut with their chest puffed out and antlers held high to show that they are fit for breeding. The bugle is also used to warn opposing bulls who are trying to take over their harem. When another bull enters its territory, a challenge ensues; the bulls wrestle with their antlers, until the weaker bull gives up and walks away.

The rut is incredible to watch (from a distance, of course), and hear.

The best place to see elk rut is at the north entrance, or at Mammoth Hot Springs.


#Pronghorn: Although, sometimes called a Pronghorn Antelope, the pronghorn in Yellowstone is not an antelope at all. They may have been referred to as “antelope” when first written about by the Lewis and Clark expedition, but time has proven that they are not related to the antelope.

Pronghorn are the fastest land animal in the Western Hemisphere, able to sprint at speeds up to 45-50 miles per hour.

A pronghorn is true to it’s name: being horned, and those horns being pronged. Their horns are shed each year, which is actually not as common as one may think—other horned mammals shed their horns, but not yearly. Male pronghorn’s horns are typically 10-14 inches, and about 70% of females have horns that are about 1-2 inches. They are easy to distinguish, with their tan bodies, white belly and unique white chest stripes.

They are typically seen in the northern range of Yellowstone.


#Wolf: Because of habitat decline and extermination, the wolf population decreased substantially during the early 1900’s. Between 1995 and 1997, 41 wolves were released in Yellowstone, and the population has grown steady since then.

In Yellowstone, a wolf pack typically consists of 10-12 wolves. There are 11 packs in Yellowstone, ranging throughout the entire park, although the majority are found north of Lake Yellowstone. Wolves defend their territory by howling and scent marking with urine. Territories in Yellowstone are an average of 165 square miles.

Wolves hunt as a pack and can effectively take down large prey. Their diet is mostly comprised of elk, but also rely on deer and bison as a source of food.

Wolves are most likely to be seen in Lamar Valley, Hellroaring Creek, Slough Creek and in the northern range.


#Bear: There are two types of bears in Yellowstone National Park, Black bear and Grizzly bear. Yellowstone is one of the few places south of Canada where black bear and grizzly bear coexist in the same habitat.

#BlackBear—in Yellowstone, only 50% of the black bears are actually black in color, others appear brown, cinnamon or blond. Their claws are short and curved, allowing them to easily climb trees, but do not allow them to dig as well as a grizzly can.

They spend the majority of the fall eating excessively, so they can hibernate properly from November to March. Birth occurs in February, when the mother becomes semiconscious to deliver her cubs, who spend the next two months with their mother in hibernation where they nurse and sleep. After hibernation, they spend two years with their mother before going off on their own. Adult males and females without cubs are solitary.

Black bears are commonly seen in the northern range and the Bechler range.

#GrizzlyBear—a grizzly bear’s appearance differs from a black bear, as they have a large muscle mass on their shoulders, and longer claws. Grizzly bears spend the majority of their time eating; as they get out of hibernation, their diet primarily consists of elk, bison, deer and carrion (dead animals that a smaller predator takes down, but then a grizzly comes along and steals their meal). Grizzly are rarely able to catch elk calves after July, and in the summer, their diet consists of various berries and grasses.

Grizzly bears are aggressive, and use this as a way to protect themselves and their young against perceived threats. As with black bears, adult grizzly bears without cubs are solitary animals.


#Badger: Badgers are burrowing mammals, characterized by short and stout bodies, with a light brown/gray body and a dark stripe down their back, and a dark face with white stripes. A badger’s diet primarily consists of ground squirrels and other small rodents. They typically need at least two ground squirrels per day to maintain their weight.

Badgers are commonly seen in the grasslands in Yellowstone.


#Fox: Foxes are the smallest canid, or "dog", found in Yellowstone. They are distinguishable by their red fur, black “boots” on the bottom of their legs, and bushy tail. The oldest known fox in Yellowstone lived to be 11 years old, when typically, they live between 3 and 7 years. Unlike coyotes or wolves, foxes bark instead of howl.

Foxes have excellent hearing; in the winter, they can locate small rodents in the snow, stalk them from above, and dive into thick snow, usually returning with prey in mouth.

They are commonly seen in Hayden Valley, Pelican Valley and in the Canyon area.


#Coyote: Although commonly mistaken as a wolf, a coyote is one-third the size of a wolf. In Yellowstone, coyotes live in packs, with up to seven individuals. It is very common to hear lone coyotes or groups howling to one another at dawn and dusk. They use this long-range vocalization to communicate with each other over long distances.

Similar to wolves, coyote populations declined in the 1900s due to loss of habitat and human interference. But they continue to thrive because their adaptability allowed them to compensate for destructive patterns.


#Marmot: Marmots are the largest rodent found in Yellowstone, weighing up to 11 pounds. They are usually seen in grassy meadows and along rocks. Marmots are best known for the chirping noise they make when excited or afraid, and the whistle they use to communicate with each other (this is why early settlers referred to them as "whistle pigs").

The best place to see marmots are Cougar Creek, Lamar Valley and Buffalo Plateau.


#BigHornSheep: Like their name suggests, male big horn sheep, called rams, are characterized by their big, curved horns. The size of their horns influences their place in the social structure. During mating season, rams fight head-on to prove dominance; this is less destructive as it sounds since there are two layers of bone above the brain that acts as a shock absorber.

Female big horn sheep also grow horns, but they are much smaller.

Horns consist of an inner portion, which is an extension of the skull, and an outer portion, which is made specialized hair follicles, similar to a human's fingernails. They are never shed like antlers are, and grow throughout the animals lifetime.

Big horn sheep are most likely to be seen on the cliffs between Gardiner and Mammoth, in the northern Yellowstone River valley and along Dunraven Pass.


#Pika: Known by their distinct whistle, a pika is most often heard before they are seen. They live in rocky alpine terrain, and will travel through tunnels in the snow in winter. Pika are commonly seen gathering grasses and other vegetation called "haystacks" to stock up on in the winter. These haystacks are built in the same location every year, and can be up to three feet in diameter-- which is about six times the size of the pika itself!

In Yellowstone, pikas are most commonly seen in Gardiner and the Mammoth area.


#Moose: Moose are best characterized by the large rack of antlers that males have for the majority of the year. Both males and females have long legs that are used to swim and wade through rivers, which is important since they diet consists of aquatic plants in the summer; they can eat up to 50 pounds of food in a single day. Typically, a moose's habitat is near marshy areas of a meadow, lake shores and along river banks.

Bulls typically shed their antlers in November or December, which allows for energy conservation and helps the survive a long, cold winter. The antlers grow back in April or May, and the bull with the largest rack maintains at the top of the social structure. During the rut, bulls challenge each other with grunts and groans, and then clash their antlers in a full on wrestling match, until the weaker of the two moves on.

The plural of moose is moose.

The best place to spot moose in Yellowstone is near the Northeast entrance and in Lamar Valley.

In addition to all of the mammals listed above, there are so many more in Yellowstone National Park. It truly is a wildlife stronghold. We think this is one of the best places on the planet to find wildlife, but we invite you to experience it yourself!

Join Nomadic By Nature for a guided backpacking trip or day hike, and see the best that Yellowstone has to offer!

This guided backpacking trip through Lamar Valley, in the northeast corner of the park, covers some of the best scenery Yellowstone has to offer. You will hike through wide-open meadows scattered with bison, pronghorn, and other big mammals, all the while following the majestic Lamar River. Eventually, the trail takes you over the mighty Mist Pass and drops into Pelican Valley — a massive expanse of rolling grass, slow-moving creeks, and a true wildlife stronghold.

Of all the trips Nomadic By Nature offers, this trip offers the best chance to see wildlife in the backcountry.

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