The focus at Elmwood Park Zoo is on animals of American origin (North, Central, and South.) The collection includes very large animals, like the massive American bison, and the very small, like the comical black-tailed prairie dog. Among the most popular animals are the energetic River Otters in the Andrew L. Lewis Wetlands Aviary, the cougars, and the spotted and melanistic (all-black) jaguars. The Zoo is also exhibits animals that are either presently endangered (like the jaguar, bison, and Chinese alligator) or represent successful returns from the endangered species list, like the bald eagle.