From Ken Grille
Great Horned Owl release October 2024, Plymouth, Ma. It's on an extremely rare occasion that get to see a a majestic Owl this close up. But on this day my friend from Cape Wildlife Center invited me to join a release of this beautiful rehabilitated animal. This GHO was not doing well when rescued, needing TLC for about a month, but seemed to be as good as new when he flew off back into the wilderness on this day. My favorite part of this sequence was right before the release when the Owl turned his head and looked right until his rescuer's eyes as if to say thank you I'm ready now. Quite a moment. And then within seconds he flew off into the thick brush to resume the life of a GHO. Note: This GHO tested negative for HPAI (bird flu) so handler did not have to wear full PPE when handling him.
We are fortunate to have a few amazing wildlife rescue centers in our area and Cape Wildlife does incredible work. They save the lives of numerous baby and adult animals and am so grateful to them for what they do. There is a link on their website to donate if you wish to help them out. (Or just click right here!)
I imagine it's getting all pumped up to fly, the eyeball version of a character licking their lips before eating something tasty. ☺️
Wait what? Do owls have an extra set of windshield wipers apart from their eyelids?
Nictitating membrane
As the other reply says, this is the nictitating membrane. A bunch of animals have them for various reasons.
Owl-natomy: Eyelids
I did this post about owl eyelids before that shows you some cool features. As a bonus, you kinda sorta but not really have a third eyelid too! Check the comments in that thread.