Mediterranean Gull

The Mediterranean gull in its full mating plumage is gorgeous, with a black head, white eye crescents, and a deeply red bill with a black band toward the end, red legs and feet and the balance of the body and wings are white with a touch of light gray in the wings. Non-breeding birds lack the black head, but have touches of black on the head. 

It is found along the coasts of the Mediterranean Sea, up through the Adriatic, Aegean and Black Seas and along the Atlantic coasts of northern Africa and western Europe and the southern coasts of England and Ireland. 

Range of the Mediterranean gull from Wikipedia. 

We saw this beautiful bird while taking the ferry from the Troia Peninsula to Setubal across the mouth of the Sado River where it empties into the Atlantic Ocean.