There are three terns commonly seen here during the winter months.
The first is the Royal tern. Photo taken at Port Aranasas
The second is the Forster's tern. Photo taken at Port Aransas
The Royal tern is twenty inches long and the Forster's is 14.5 inches long. The difference is size is apparent in this photo. Photo taken at Padre Island National Seashore
The third tern is the Caspian tern. Photo taken at Port Aransas