American Herring Gull (Juvenile)
I had a hard time identifying this bird because of his coloring. They go through 4 color stages, with the adults being basically grey and white. (Their legs and feet stay pink throughout). See this chart by National Geographic;
http://animals.nationalgeographic.com/animals/birding/herring-gull/

The American Herring Gull or Smithsonian Gull or is a large gull which breeds in North America. It is often treated as a subspecies of the European Herring Gull but is now regarded as a separate species by some authorities.
Similar species: Shorebirds And Allies
By Lilygirl
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Uploaded Sep 13, 2014. Captured Apr 28, 2007 21:13 in Olmsted Road, Monterey Regional Airport (MRY), Monterey, CA 93940, USA.