IN EARLY 2022, the University of California Press will publish my second book, The Accidental Ecosystem: People and Wildlife in American Cities. It tells the story of how cities across the United States went from having little wildlife a century ago to filling, dramatically and unexpectedly, with wild creatures. Today, many American cities have more large and charismatic wild animals living in them than at any time in at least the past 150 years. Why have so many cities—the most artificial and human-dominated of all Earth’s ecosystems—grown rich with wildlife, even as wildlife populations have declined precipitously in most of the rest of the world? And what does this paradox mean for cities, people, wildlife, and nature on our increasingly urban planet? 

THE ACCIDENTAL ECOSYSTEM argues that although cities were not built with the goal of attracting wild animals, they have become rich wildlife habitats, or even weird wildlife refuges, because of decisions people made often decades ago and mostly for other reasons. The recent explosion of wildlife in American cities is one of the greatest ecological success stories since the dawn of conservation, but it happened largely by accident. Only over the past generation have scientists, conservationists, planners, and civic leaders throughout the United States begun to study, grapple with, and appreciate cities as fertile ecosystems housing diverse, multispecies communities. But bringing these animals back was the easy part. The hard part, and the real work ahead of us, is living with them now that they’re here.