For a while now you've probably been hearing about bookbands, how they're gaining momentum everywhere in Texas, in Missouri, Florida, and Pennsylvania.

On the Code Switch Podcast, we're taking a look at why.

Why are so many books suddenly considered so dangerous to kids?

Listen to our new series on the Code Switch Podcast from NPR. are.

What do Bison, beavers, wolves, and sea otters all have in common?

They're keystone species.

That means they have an outsized impact on their ecosystem.

It took humans driving some of these animals to near extinction to realize just how important they are.

We've spent decades since then reintroducing endangered species into their original habitats, sometimes using very interesting techniques.

Every summer for years past, Idaho Beaver have been on the move in this manner.

Countless numbers have been supplied for streams and lakes to bring the beaver population back to its former position.

Ear tags are attached for future information.

The drop crates are loaded into the airplane.

Parachutes are attached to cargo lines.

10 boxes to a load, 20 beaver, ready for the flight to Mountain Meadows.

Now, into the air and down they swing, down to the ground near

a stream or a lake. The box opens and a most unusual and novel trip ends for Mr Beaver.

That's from a video shot in the 1950s by Idaho Fish and Game

detailing how they used to relocate beavers by airplane.

Now animals like the North American Beaver and American Bison

are some of the 1973 Endangered Species Act's most notable success stories.

I don't think they tried to drop a bison from the air.

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