This is an adult Herring Gull, with a Royal Tern behind it. Couldn't crop out the Tern without cutting the gull's tail. Enlarge to see the red (or pink) on the beak. Thought something was wrong with the photograph, then saw the same in the reference books.
The Herring Gull is larger than the other gulls on the Florida gulf coast. They draw the attention just by size. This photo was taken at Fort DeSoto Park last week. Fort DeSoto Park was voted the 2005 #1 beach in North America.