A keystone species is an organism that defines and supports an entire ecosystem, filling a vital ecological niche. Without these species, ecosystems would be radically altered or even collapse. This full-color, pocket-sized field guide by best-selling naturalist Collin Varner highlights fifty keystone birds, mammals, amphibians, insects, fish, shellfish, and mollusks found across the Pacific Northwest bioregion. Each entry features clear photography, etymology, descriptions, habitat information, and risks and warnings. This convenient and easy-to-use reference is perfect for walkers, hikers, campers, beachcombers, sailors, paddlers, and whale watchers and important for raising awareness of the need to conserve and protect these vital species. -- back cover.