Abert's squirrels (Sciurus aberti) are a North American species, found across a range of locations. Kaibab squirrels (Sciurus aberti kaibabensis) are a subspecies of Abert's squirrels, found only in one area in the United States. As these two types of squirrels have been isolated from one another for 10,000 years, they've evolved some distinct and separate characteristics.