This Turkey Tuesday is about a wild turkey’s eyes. Every turkey hunter knows that turkeys have keen vision, and that vision is the bird’s primary way of detecting danger. But have you ever looked at a wild turkey’s eyelids? If you look closely at a wild turkey’s eyes, like the tom in this picture sent to me by Joe Foster, you can clearly see their eyelids. Turkeys actually have 3 eyelids, the upper and lower ones are obvious and specific to turkeys, they raise the lower lid upwards to close their eyes. But turkeys also have a third eyelid, called a nictitating membrane. Nictitating simply means to blink, but unlike the upper and lower eyelids, the third eyelid closes from the inside part of the eye to the outside – horizontally across the eye. The purpose of the third eyelid is to maintain moisture on the eye surface while also cleaning and protecting the cornea. In fact, turkeys can control blinking with this third eyelid, so it may be drawn across the eye when toms are fighting, or when an individual bird is flying, walking through heavy cover, or otherwise behaving in a way where eye damage is possible. In some birds, it appears that the third eyelid is involved in male displays when they’re courting females, although whether this is the case in wild turkeys is unclear. The take home is, the nictitating membrane helps protect a bird’s eyes and allows them to fully rely on their vision to survive.