How far can eagles see?
Studies suggest that some eagles can spot an animal the size of a rabbit up to two miles away. In part, eagles have excellent vision because their eyes, which are very large in proportion to their heads, are densely packed with sensory cells. While humans typically have 200,000 light-sensitive cells per square millimeter of retina, eagles may have 1 million — five times more. Similarly, while humans have only one fovea, a funnel-shaped part of the retina where vision is sharpest, eagles have two. Finally, where people see just three basic colors, eagles see five, enabling them to pick out even well-camouflaged prey.
