There were two adult Ring-billed Gulls at Nimmo's Pier during our stay and were seen on each visit whilst on the 24th a third bird was found on the other side of the harbour at the end of Long Walk near the outfall. Each of these birds are detailed below. I have shown each bird facing in the same direction to allow for comparison.
Bird 1: This bird had the heaviest head streaking, note the dark mark at the rear of the pupil.
Bird 2: The second of the regular slipway bird had the lightest head streaking: note the clear eye
Bird 3: The Long Walk outfall bird: note the dark mark in front of the eye (just visible in this image)