White and grey bird
San Diego County, California, US
3rd photo shows a nice size comparison between this species and Western Gull.
The Glaucous Gull (Larus hyperboreus) is a large gull which breeds in the Arctic regions of the northern hemisphere and the Atlantic coasts of Europe. It is migratory, wintering from in the North Atlantic and North Pacific oceans as far south as the British Isles and northernmost states of the USA, also on the Great Lakes. A few birds sometimes reach the southern USA and northern Mexico.