This guy has a suite of characters that could lead the uninitiated to think this he
is more than he is.  The eye is ivory white.  The orbital ring is pinkish.  There's a
dark gray smudge of feathering through the feathers around the eye.  The white
skirts are longish and there's a lot of black in the tail.  There is also small mirrors
on the under side of the outer most primaries.

So, one might be tempted to call is a Slaty-backed Gull....