American Herring Gull on this blog for too long. This common species is likely what most people are thinking of when they use the term "seagull". Abundant in the northeast, they have been expanding their Atlantic breeding range southward. European Herring Gulls are very similar and considered the subspecies larus argentatus argentatus. The Herring Gull group taxonomy is complicated and, apparently, controversial. You can read more about it on Cornell's "The Birds of North America Online" here.