The elk are the most abundant large herbivores in the Yellowstone ecosystem. There are thousands and thousands of them. They migrate in and out. And those migration routes need to stay open.

As I started to read nonfiction in the mid '70s, I discovered, holy cow, there was a lot of imaginative nonfiction. Not the kind where people use composite characters and invented quotes. I hate that kind of nonfiction. But imaginative in the sense that good writing and unexpected structure and vivid reporting could be combined with presenting facts.

Whether you like the label 'Anthropocene' or not, whether you find the prospect of what it signifies inevitable or appalling (or both), the time has come to address its implications, as these thoughtful, battle-tested authors attempt to do. The time has long since come.

The elk are the most abundant large herbivores in the Yellowstone ecosystem. There are thousands and thousands of them. They migrate in and out. And those migration routes need to stay open.

By the cold Darwinian logic of natural selection, evolution codifies happenstance into strategy.

But private lands development around the periphery of the parks - Grand Teton and Yellowstone - is a crucial issue because if those private lands are transformed from open pastures, meadow, forest land to suburbs, to little ranchettes, to shopping malls, to roads, to Starbucks - if those places are all settled for the benefit of humans, then the elk are not going to be able to migrate in and out of Yellowstone Park anymore. And if the elk can't migrate into the park, then that creates problems for the wolves, for the grizzlies, for a lot of other creatures.

I wrote four novels, but then I realized that the world didn't need me to be a novelist, but the world could use me as a nonfiction writer.