Eagles have unusual eyes. They are very large in proportion to their heads and have extremely large pupils. Eagles’ eyes have a million light-sensitive cells per square mm of retina, five times more that a human’s 200,000. While humans see just three basic colours, eagles see five. These adaptations gives eagles extremely keen eyesight and enable them to spot even well-camouflaged potential prey from a very long distance. In fact the eagles’ vision is among the sharpest of any animal and studies suggest that some eagles can spot an animal the size of a rabbit up to two miles away!