Sentence:  A cloud of sea birds hovered overhead, the gannets diving with folded wings, while the black <WSD>noddy</WSD>-terns fluttered down in companies each time the fish drove the small fry to the surface. 
Meaning of the word marked with <WSD> tags:  Any of several stout-bodied, gregarious terns of the genera "Anous" and "Procelsterna", found in tropical seas.