But before checking out the warblers, I went to scan the water as there had been reports over the last few days of a Caspian Tern, though I didn't think it was likely I'd find one. Just when I was satisfied that all the birds on the water were gulls and there wasn't a Tern present, I saw a large white bird dive into the reservoir. Gulls don't usually do that! It was quickly obvious that this was the Caspian Tern when I spotted that thick bright orange bill and dark underwing primary feathers. The bird circled for the next 10 minutes as we watched before I lost sight of him.