From the Great Smoky Mountains to Point Reyes National Seashore, America's national parks are home to some of nature's great wildlife spectacles. Here, Gary W. Vequist and Daniel S. Licht, two veterans of the National Park Service, focus on twelve animals that have been imperiled and at risk, but are now protected within the National Park System.

Showcasing one species for each month of the year, including gray wolf, black bear, prairie dog, sea turtle, bison, bats, salmon, elk, beaver, American alligator, gray whale, and bald eagle, Vequist and Licht pair each premier species with a...