Emily Kwong (host, with guest Nell Greenfield‑Boyce also speaking within these segments)

The thing is, most collisions are not happening, like, way up in the sky, right?

So it's not like it's just a skyscraper issue.

Most collisions are happening down low.

Oh, really?

Like below the tree line when they come down to rest.

And so one to three story buildings like homes, that accounts for a lot of the bird deaths just because there's so many of those buildings.

But, you know, in cities, there are lots of buildings close together so people can like walk a set route every morning.

And in these cities, it's become clear that a small number of buildings are

seem to account for a lot of the deaths.

They have architectural features that are just like death traps.

We call this the walkway of death.

So this is a very deadly spot.

So that's another volunteer in DC I walk with, Stephanie Dahlke.

She showed me this skyway between two buildings.

It's made of mirrored glass.

And right near it, we found a dead, ruby-throated hummingbird.

That's a little iridescent green bird.

It's like no bigger than your thumb.

So do the birds just think certain buildings are more sky-like?

Yeah.