Royal Tern 1
(I.D. courtesy of Peter May)

These were also fairly common down there, but were much harder to photograph than the Laughing Gulls. They're generally flying much faster, and don't seem to 'hang around' some areas like the gulls do. I was able to get a few shots while they were feeding at one of the small ponds on the island. Canon 100-400 at 400mm, ISO 100, f/5.6 and 1/500 second (hand-held).