I am six years, and my question is why do bisons live in herds, and how big are their herds?

So that's a really good question, Leo.

So bison are social animals just like humans.

You know, they, they just, they like being around each other.

And living in big herds can have important advantages like protection from predators, having a helping hand or, or hoof to raise your baby bison, or learning from older bison about where to go to find good food and water.

Before 1800, there were somewhere between 30 and 60 million bison roaming North America.

There are stories from explorers and Native Americans of herds that were so huge that they stretched all the way to the horizon, and the ground literally shook as they passed.

My question is what's their role in the ecosystem?

What is that? What role do they serve in the grasslands?

Yeah, totally.

So in general, when we say keystone species, we mean an animal, uh, an organism that, like, has a disproportionately large effect on an ecosystem, uh, relative to, you know, let's say its biomass.

Prairie dogs are food for a huge variety of species out on the prairie.

Prairie dogs physically modify the environment in a ton of ways, so they build burrows that other species use, they graze vegetation to create this really short grass habitat that a lot of animals like to nest and forage in.

They can't stand to have any sort of, like, vertical structure in their colonies, probably because they like to have long sight lines, they don't like perching places for predators.

Yeah, I mean, if prairie dog populations shrink, what's at stake for the grassland ecosystem? Especially considering how much carbon is stored in grasslands.

Yeah, we know that intact prairie holds way, way, way more or sequesters way, way, way more carbon than tilled agricultural lands.