Very large bill here compared to Sibley's illustration for Common Tern, Al. The dark feet also don't fit the breeding color of orange for the Common Tern. This may more likely be Caspian Tern (which I've never seen in the wild). The adult sizes are 12 and 21 inches respectively for the two species. Can you vividly recall the size of the bird? That will be the clincher for the bird's ID.
