USA National Parks: Biodiversity in Yellowstone

Yellowstone National Park is one of the 61 National Parks that can be found on our USA National Parks Push Pin Maps. It is situated in a vast geological landscape and crosses the boundaries of three states: Wyoming, Montana and Idaho.

Yellowstone is one of the most renowned parks in the United States. What distinguishes this park from the others? Aside from being the oldest national park in the United States, it is also the second oldest in the world (Bogdkhan Uul in Mongolia was established in 1778). Designated as a national park in 1872 and a UNESCO Heritage site in 1978, Yellowstone boasts unique geothermal features, stunning scenery and an abundance of diverse species that co-exist within the park.

This post will focus on the wildlife that can be found within the park and an insight into the greater Yellowstone ecosystem. Let's begin!

Commonly referred to as a Buffalo, the American Bison is the official national mammal of the United States. While there were 25-30 million Bison in North America in the 16th century, they were hunted extensively for fur and game in the 19th century and reduced to less than 100 in the wild by the end of the 1880s. Out of this number, there were about 23 Bison left in the greater Yellowstone area. 

In 1905 the American Bison Society (ABS) was created to protect the species from extinction. The ABS reintroduced Bison into wildlife refuges in various states and monitored their numbers until the organization was disbanded in 1935. Today there are around 5,000 Bison in Yellowstone.

Bison sightings within the park are very common. Visitors are warned to stay at least 25 yards away from Bison as they became aggressive when provoked and can easily outrun humans. Between 1980 and 2000, Bison related injuries within Yellowstone were three times as common as Bear related injuries.

While the Bison's size serves as protection from most predators, young Calves are often targeted by packs of Wolves. When this occurs, adult Bison will form a shield around their young and attempt to ward off the attack as a group. This increases the Bison's chances of survival compared to animals that split up and run away, such as an Elk. 

Numbering between 10,000 and 20,000 during summer and less than 5,000 during winter, Elk are the most populous large mammal in Yellowstone. Elk are essential to the park's ecosystem as many predators feed on them, including wolves, bears, mountain lions and coyotes. 

During a period of mating known as the rut, male Elk become aggressive towards each other and will fight to show dominance. Other behaviors during this time include rubbing their antlers on trees, wallowing in mud and loud vocalizations. 

Elk can be found in various areas within the park and are frequently photographed due to their large antlers, which are shed once every year. Similar to Bison, visitors are advised to stay at least 25 yards away from Elk as they have been known to charge after humans and ram cars with their antlers.

Bighorn Sheep occupy the mountainous terrain in Yellowstone's Northern section. They spend most of their time navigating steep slopes as a way to protect themselves from Wolves, Mountain Lions, Coyotes and other predators. Male Rams have large horns that curl back towards their jaw while female Ewes grow smaller horns with less curvature. 

Similar to Elk, males engage in aggressive behavior during mating season in an attempt to show dominance and maintain preferential access to Ewes. They use their horns to charge and attack other males at speeds of up to 20 miles per hour. Rams with larger horns often dominate the social structure and have the greatest chance of mating. 

While both Grizzly and Black Bears can be found in Yellowstone, the two can be difficult to differentiate. Grizzly Bears are larger than Black Bears and have an area of muscle that sticks up above their shoulders. They are also much more aggressive and can pose a serious threat to humans if proper safety precautions are not met. 

When hiking on trails in Yellowstone, visitors are advised to carry bear spray and bear bells. The bells serve to create a continuous noise and minimize the chances of surprising a bear in close quarters. Generally speaking, a Grizzly Bear will only attack a human if they are protecting a cub or a recent kill and become startled. Visitors are advised to keep a distance of at least 100 yards from bears, which is four times the recommended distance from a Bison or Elk. 

Adult Male Bears are at the top of the social hierarchy and have access to the best habitats and sources of food. Younger Bears that have recently left their mother are more susceptible to dangerous living conditions near roads or developed areas.

Yellowstone is home to many other mammals such as wolves, foxes, coyotes, mountain lions, bobcats, lynx, cougars, moose, deer, pronghorn and badgers. Each species has its own distinct effect on the national park and collectively they form the diverse Yellowstone ecosystem. 

Interested in seeing these animals for yourself? You can find more information on the National Park Service Website including top things to know before visiting, lodging options and bear safety precautions. 

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