A keystone species is an organism that defines and supports an entire ecosystem, filling a vital ecological niche. Without these species, the ecosystem would be radically altered or even collapse. This pocket-sized field guide by bestselling naturalist Collin Varner highlights 50 keystone birds, mammals, amphibians, insects, fish, shellfish, and mollusks found across the Pacific Northwest bioregion—including the American Crow, Bald Eagle, American Beaver, California Sea Lion, Sea Otter, Orca, Coyote, Grizzly Bear, Giant Pacific Octopus, Chinook Salmon, Pacific Tree Frog, Pacific Banana Slug, Mixed Bumblebee, and more. Each entry features clear photography, etymology, descriptions, habitat information, risks and warnings. This convenient and easy reference is perfect for casual walkers, hikers, campers, beachcombers, sailors, paddlers, and whale watchers, and draws awareness to the importance of conservation and protection of these crucial species.