Cooper's Hawk (Male) Part 4 of 4

n fact, all birds have one: a transparent fold of skin that sweeps sideways across the eye to clean and moisten the cornea. The membrane’s inner surface is covered with brush-tipped cells that lubricate the cornea’s surface with tears. Some birds, including falcons, have a special gland that produces a thick fluid to moisten the cornea. When a peregrine falcon stoops on its prey, flying at up to 240 miles per hour, the nictitating membrane keeps its eyes from drying out. It can be deployed as a bird flies against the wind, or in rain or snow. It may also protect a raptor’s eyes from the sharp claws or teeth of flailing prey and the sharp beaks of its own nestlings.
http://baynature.org/articles/natures-sa...

Here is a great link and images on eye color vs age and nictitating membrane.
http://www.themodernapprentice.com/eyes....

Thanks Christy. Whenever I see a Raptor,I remember Emily and U!!

I did see this, Jemma...Nictitating membrane helps with the wind when the birds are flying...Peregrines in their stoop, accipiters in their chase, etc...great series!!

Thanks, Braulio.

Oh, there it is.
: ]

BTW ,thanks Jellis.

Concord is usually warm. It was mid afternoon and quite warm. I also saw a green metallic bee which usually comes out only when it is warm.
You are probably correct.

Thanks Argy. A small observation ,but an observation none the less.

Well done.

My pleasure!

Thanks for your valuable feed back, Suzanne.

Camels and sharks. Hmm. While I was checking it out on Google, I read that we humans have the remnant of nictitating membranes in our eyes, as do most mammals. I wonder why we lost them. Off with me. Nice to chat with you, great photos.

maybe it was occasionally moistening it! My daughter has been complaining of dry eyes.

Sorry! Should read, "a kind of second eyelid" ... what a weird error.

I thought that's what it was, but honestly, I had to read up on it to make sure. Some reptiles and birds have nictitating membranes in their eyes, a kind of third eye. It can be drawn across the eye to moisten it ... while still allowing the animal to see, though not quite as well. Toss it in Google for more examples, details and such.

I am not sure why it appeared.Though I dohave some info on nictitating membrane
They also have a third eyelid that slides in from the side and is clear. This is called the nictitating membrane and it protects the bird from injury while going down into long grasses to grab prey. Sharks and camels also have nictitating membranes. Why would camels need it? To keep sand out of their eyes!http://www.smm.org/warnernaturecenter/animals/hawk

Thanks Suzzane. Why does it show up occasionally?

Nictitating membrane, most likely?