They're in one of the most remote parts of the United States, to see something spectacular that happens every year.

An icon of the American West.

This is a sage grouse.

And this is its mating dance.

The sage grouse once numbered in the millions across this entire region.

But today, they are on the verge of endangerment.

And the area they live on has shrunk by half.

That's a problem.

And not just because it's fun to look at.

It's because the sage grouse is actually really important.

And to understand why, you have to understand its dance.

This is a female sage grouse.

And this is a male sage grouse.

During mating season, it's big and flamboyant looking, all so that it can attract mates.

It's sort of like a peacock in that way.

The spiky tail, the puffed out chest - they don't serve a clear function except to be attractive.

These white feathers on its chest are rough and spiky.

And for the first step of its dance, the sage-grouse takes a deep breath, and it swishes its wings against those spiky feathers.

It sounds like this this.

These yellow things are its vocal sac.

It's actually one esophagus with a strong muscle in the center.

When the sage grouse takes in a gulp of air, it contracts.

When it breathes out, the vocal sac pops.

That sounds like this.

Female sage grouse can hear these sounds from up to two miles away.

And then it's a competition.

The strongest male dancers crowd out the weaker ones.

The winner gets to mate with most of the females.

After they mate, the females go up to ten miles away to nest.

But this arena, where the competition goes down, that place stays the same every year.

Sage grouse live across this whole vast area.

But year after year, they each come back to do the courtship ritual in the same exact spot - one of these blue dots.

It's why sage-grouse watchers always know where to find them.

That mating area is called a lek.

And it's a big part of why sage grouse matter so much.

Coming back to the same place every year means that sage grouse are really easy to keep track of.

Some leks have been monitored by researchers for more than 75 years.

They're so easy to count that conservationists consider them an indicator species.

That means they use the number of sage grouse as a sort of proxy for how healthy the entire sagebrush ecosystem is.

If sage grouse are doing well, there's a good chance that elk, and pygmy rabbits, and the 350 plant and animal species in the region are doing okay too.

That also means that if you want to protect wildlife in the American West, figuring out how to protect the sage grouse is a good strategy.

In 2008, Wyoming implemented a new policy aimed at protecting the bird.

It ended up also having major benefits for another animal - the mule deer.

But because sage grouse are so easy to count, we also know that they are in trouble.

The lek is where the sage grouse mates, but it's just the epicenter of a much larger range where they live.

And in order for them to keep coming back to the lek to reproduce, sage grouse need the entire range to be undisturbed.

That means if human activity alters this range, they tend to not return to the lek - they don't reproduce.

Montana started keeping track of sage grouse leks in 2002.

Since then, their population in the state has fallen by nearly half.

There are a lot of reasons for this decline: invasive plant species, wildfires, but a big one is drilling and mining.

Western states have increased production dramatically in recent years.

A huge amount of new oil.

Oil, coal, and natural gas dominates the landscape and the economy.

Wyoming has the most sage grouse of any state.

Here's a map of leks in Wyoming.

And these are oil and gas fields.

In 2015, governors from four states announced a plan with the federal government to protect the sage grouse.

It banned mineral mining across ten million acres of sage grouse habitat.

And it restricted oil and gas leasing in 13,000 square miles of the most critical habitat areas.

It was hailed as the largest conservation effort in U.S. history.

But today, Donald Trump's administration isn't enforcing the restrictions on oil and gas leasing.

And it canceled the ban on mining here.

And the numbers reflect that: since he took office, oil and gas leasing on public land in the U.S. has skyrocketed.

And on land the 2015 plan was supposed to protect, leasing has gone up tenfold.

Today, officials predict that sage grouse numbers will keep falling.

The sage grouse is an indicator species.

It means that the sage grouse can tell you a lot about the health of the entire sagebrush ecosystem across the American West.

But they can also indicate something about American policy.

About the power that fossil fuel and mining companies have over government.

About what we choose to protect.

And what we don't.