This is fresh air. I'm Terry Gross. Roadkill. You've probably seen your share of it and maybe even accidentally killed an animal on the road.

Cars are weapons of death for wildlife, large and small that live in wooded areas near the road,

from salamanders to birds, skunks, possum deer, mountain lions and bears.

The roads themselves are problems too, cutting off animals from their sources of food, migration paths,

animals to mate with, even messing with evolution.

The dire threats roads have created for animals and ways to eliminate or at least moderate those threats.

Well, put it all together and you've got what's called road ecology.

The world of road ecology is filled with fascinating insights into animal behavior,

the threats they face from roads and solutions that have been tried.

I just learned about this in the new book Crossings,

how road ecology is shaping the future of our planet.

My guest is the author Ben Goldfarb.

His previous book titled Eager, the surprising secret life of beavers and why they matter,

won the Penn E.O. Wilson Literary Science Writing Award.

Goldfarb has been published in the Atlantic, National Geographic and the New York Times.

He lives in Colorado.

Ben Goldfarb, welcome to Fresh Air.

I want to say, am I the only person who didn't know what road ecology was?

No, you're certainly not.

You're in the vast majority in not knowing what road ecology is.

Good, so let's talk about it.

I want to start with what you say,

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