I thought this was quite interesting: it’s a couple of consecutive shots of a bald eagle, with not-quite fully adult plumage, which I took at the weekend at the Raptor Foundation. In the first shot you can see the nictitating membrane. By complete coincidence, when I’d decided to post these and checked for the spelling of the word, one of the example shots shown on the Wikipedia entry is of a bald eagle as well.
These are cropped by hand, so the proportions may not be identical. I have a few more in my Birds set on Flickr.