Devils Lake is located in the heartland's prairie pothole region. As the glaciers retreated some 10,000 years ago, they left thousands of small depressions, sometimes called potholes, "kettles" or sloughs, that collect water. These wetlands stretch from north central iowa diagonally across North Dakota to the Canadian province of Alberta, and are prime waterfowl habitat, providing viewing areas for snow and blue geese, ducks and grebes. Woodland birds unique to North Dakota settings are abundant, such as warblers, flycatchers, Baltimore orioles and woodpeckers. Other bird species worth looking for are the common goldeneye, red-necked grebe, Forster's tern, cormorants and northern waterthrush.
Although mixed grass prairie is the predominant natural vegetation of this region, the woodlands associated with Devils Lake make up a large portion of Grahams Island's natural vegetation. The densely wooded parklands at Grahams island and Black Tiger Bay support bur oak, northern hackberry, green ash, American elm and boxelder. North Dakota's state flower, the prairie rose, blooms in abundance at Grahams Island. Some of the wildlife found in the parks include red fox, raccoon, squirrels, white-tailed deer, coyote and beaver, as well as wild turkeys. Moose have also been spotted.