One of the oldest and most famous parks in the world is getting a helping hand from the reintroduction of some huge, hairy, four-legged mammals.

The amazing bison of Yellowstone National Park are acting like super-heroes, “reawakening” the land and making it healthier than it’s been in over a hundred years.

Yellowstone, in the United States, is known for its amazing wildlife and scenery.

Scientists have watched closely as the park’s bison herd has re-grown, and what they found is incredible! The 5,000 bison that roam across the park are doing three important jobs that are fixing the ecosystem: grazing, trampling, and fertilizing.

How Bison Become Park Builders

These shaggy animals aren’t just walking around; they are hard at work!

1. Natural Lawn Mowers (Grazing): When bison eat the grass, they don’t eat it all the same way. This creates a mix, or a “mosaic,” of different habitats. Some patches of grass are short, which other small animals like, and some are left tall for different insects and birds. This variety is great for nature.
   
2. Nature’s Gardeners (Trampling): As the bison walk, their heavy hooves break up the hard dirt. This makes little dips and pathways, which helps rainwater soak into the ground instead of running off. It also helps new types of seeds find a place to grow.
   
3. Super-Fertilizer (Fertilizing): The bison’s waste acts as a natural, healthy fertilizer. This helps the grass grow back even stronger. Scientists discovered that the grass in areas where bison graze is a whopping 150% richer in protein. That’s like turning regular grass into a delicious, healthy superfood for every other animal in the park.

A Glimpse into the Past

An expert named Bill Hamilton said this revival is “a reawakening” of what the land used to be like long ago. Before the 1800s, huge herds of bison roamed freely. They were nearly wiped out, and the land suffered without them.

Now, their return is showing everyone what was lost and how vital they are. By moving and living naturally, the bison are helping the entire food chain—from the smallest insects right up to the biggest predators.