Herring Gull
Larus argentatus
At a recharge basin in Glendale Arizona, USA. 3 January 2016. This example is an immature with much brown in the plumage.
Herring Gulls are normally uncommon at lakes and ponds in the Sonoran Desert and common at the sea coast in Sonora during the winter migration. Their large size may be the first clue to separate them from the much more common Ring-billed Gull. Some authorities separate the American Herring Gull from the European Herring Gull.