Birds have better eyesight than humans. A hawk can spot an insect as small as a cricket from 30 metres in the air. A hawk’s eyesight is 1,000 times sharper than a human’s. But it’s more difficult for a bird. Unlike humans, they can’t move their eyeballs. There is another difference between human eyes and bird eyes. Birds have a third eyelid between the upper and lower lid. This eyelid is transparent and moves from side to side instead of up and down, like a sliding cupboard door. It protects the eye from dust and harmful rays from the sun. (An eagle can look directly at the sun.)