According to William Hodos, a distinguished professor emeritus at the University of Maryland who has studied the visual acuity of birds since the 1970s, two eyeball features confer eagles' sharper vision. First, their retinas are more densely coated with light-detecting cells called cones than human retinas, enhancing their power to resolve fine details just as higher pixel density increases the resolving power of cameras.⁠ ⁠ Second, they have a much deeper fovea, a cone-rich structure in the backs of the eyes of both humans and eagles that detects light from the center of our visual field. "Our fovea is a little shell or bowl, while in a hawk or eagle, it's a convex pit. Some investigators think this deep fovea allows their eyes to act like a telephoto lens, giving them extra magnification in the center of their field of view," Hodos said.⁠ ⁠ On top of sharp focus and a central magnifier, eagles, like all birds, also have superior color vision. They see colors as more vivid than we do...