When the deer killed off the forest, they decided to let the wolves loose to fix it. We had no idea what exactly we had done.
One of the most exciting scientific findings of the last 50 years is called a trophic cascade.
A trophic cascade starts at the top of the food chain and tumbles to the bottom. One of the best examples of this happened in Yellowstone National Park in 1995 when wolves were reintroduced.
Wolves are really good at eating deer. But as it turns out, because of their deer diet, they also help lots of other animals survive.
Humans killed all the wolves in Yellowstone National Park 70 years ago. And the deer population exploded.
Humans, being the controlling type in our relationship with Earth, tried to control the deer population. But deer are super-good at showing each other lots of love ... so the population grew and grew. In 1995, we reintroduced wolves to the park, and they immediately started killing the deer. But that`s the least remarkable part. The wolves actually started changing the behavior of the deer.
Deer started avoiding certain parts of the park — mostly the places where they could easily be trapped.
And those areas started to regenerate! The trees grew five times the height they had been!
Barren parts of the land became lush forest filled with new animals. Songbirds moved back in because of all the new trees!
Beavers loved the new trees, so they started moving in too! They built some dams, and that created ponds in the rivers. Ducks, muskrats, otters, and fish moved in.
The wolves started killing coyotes, and that allowed for mice and rabbits. Which brought foxes, weasels, and owls back to the park.
Bald eagles and hawks decided they wanted in on the action too.
Then grizzly bears moved back as well!
You see, the new trees were suddenly growing berries they could eat and thrive on.
The wolves even changed the behavior of the rivers. With less erosion, more pools formed, and the rivers stopped meandering. They became more fixed in their course.
Wolves changed not just the ecosystem, but its actual topography.
We are all connected. And what we do to other species affects you and me.
Now, go hug a tree and thank a wolf today.
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