On my second day in San Diego, I met another photographer who was trying to get an image of just the Pelican's eye. I decided to do something similar, though I was going for more of a tight head shot rather than just the eye. This was taken about 6m away from the Pelican with my 800mm lens (and 6m is the minimum focusing distance of that lens). In retrospect, I should put my 7D on there and gotten more eye detail and should have used some extension tubes to get even closer.
Pelican Eye - Canon 1Ds3, 800 f/5.6 IS, f/7.1, 1/500s, ISO 200.