During a time when most wild animals are experiencing decline in the face of development and climate change, the intrepid mountain lion - also known as a puma, a cougar, and by many other names - has experienced reinvigoration as well as expansion of territory. What makes this cat, the fourth carnivore in the food chain - just ahead of humans - so resilient and resourceful? And what can conservationists and wild life managers learn from them about the web of biodiversity that is in desperate need of protection?

Some 40 million miles of roadways encircle the earth, yet we tend to regard them only as infrastructure for human convenience. While roads are so ubiquitous they're practically invisible to us, wild animals experience them as entirely alien forces of death and disruption. In Crossings, environmental journalist Ben Goldfarb travels throughout the United States and around the world to investigate how roads have transformed our planet. A million animals are killed by cars each day in the US alone, but as the new science of road ecology shows, the harms of highways extend far beyond roadkill.

Late one June night in 2011, a large animal collided with an SUV cruising down a Connecticut parkway. The creature appeared as something out of New England's forgotten past. Beside the road lay a 140-pound mountain lion. Speculations ran wild, the wildest of which figured him a ghostly survivor from a bygone century when lions last roamed the eastern United States. But a more fantastic scenario of facts soon unfolded.

North America's biggest cat was once killed for bounty dollars, slaughtered with impunity and driven toward extinction. But today's cat of intrigue, despite our lingering fears and misconceptions, has returned to much of its native range in the western United States and gained respect as a predator integral and necessary to wild ecosystems. This turnaround was triggered by one man: Maurice Hornocker. Cougars on the Cliff recounts the early years of his research when he tracked lions following a dog's nose and footprints in the snow—before telemetry was available.

In 1908, near Folsom, New Mexico, a cowboy discovered the remains of a herd of extinct giant bison. By examining flint points embedded in the bones, archeologists later determined that a band of humans had killed and butchered the animals 12,450 years ago. This discovery vastly expanded America's known human history but also revealed the long-standing danger Homo sapiens presented to the continent's evolutionary richness. Distinguished scholar Dan Flores's ambitious history chronicles the epoch in which humans and animals have coexisted in the "wild new world" of North America.