double pupil

Ive searched all over the net for this but to no avail. Does anyone know anything about the double pupil of an oystercatcher?
thanks,
Jared

Try here and there are a few other links within the thread.

http://www.birdphotographers.net/for...ad.php?t=45547

Bill

Thanks for pointing to the thread Bill. So Jared, we really don't have a double pupil but just an illusion of one caused by dark pigmentation of the surrounding iris.

Here is another thread about this: http://www.birdphotographers.net/for...ad.php?t=15001