Eyes: Chickens have better vision than people, by several measures. Their ability to bring objects into sharp focus and to notice very small differences in color is better than human vision, even in newly hatched chicks. Chickens can even see ultraviolet light. (Unless you have super-human powers, you can’t.) In case you were wondering, the most common chicken eye color is reddish-brown.
A chicken’s upper and lower eyelids aren’t meant for blinking. Instead, chickens have a third eyelid for that — the thin, translucent nictitating membrane. When it’s not in use, the third eyelid is stowed in the corner of the eye nearest the beak. It acts like a windshield wiper, or sometimes, safety goggles.
A chicken reflexively pulls the third eyelid up over the eye whenever she needs to clear some eye gunk or avoid flying debris (or a kid’s curious finger). When a chicken is sleeping, the lower lid is pulled up to close the eye; the upper eyelid doesn’t move much.
