The Herring Gull is the most numerous, widespread, and adaptable of the large gulls that breed in North America. It nests in many different habitats, including Arctic tundra, small lakes in the boreal forest, natural and artificial islands in the Great Lakes, rooftops in cities, windswept islands in the Atlantic Ocean, and barrier beaches and saltmarshes in the eastern United States. It feeds on a diverse array of foods in a wide variety of habitats, including shellfish and crabs in intertidal zones, fish in lakes and oceans, earthworms and arthropods in farm fields, berries on barrens in Maine and Newfoundland, fish waste and by-catch discarded by fishing boats on the outer continental shelf, food of domestic animals at industrial farms, and human refuse.
At least in the southern part of their range, Herring Gull populations have fluctuated enormously during the past 150 years. Their eggs are palatable and nutritious, and have been harvested for human food for centuries or perhaps millennia, which probably limited the numbers and distribution of the species wherever it was encountered by human populations. Herring Gulls were killed in large numbers for the millinery trade in the late 19th century, to the point at which they were regarded as endangered and were actively protected at the dawn of the conservation movement in North America. Within a few decades, however, the species had increased so rapidly, had spread so far down the Atlantic coast, and was interacting with humans so extensively, that it was regarded as a pest and was then intensively persecuted. Since the 1980s, the Herring Gull has been decreasing once again and has now become a candidate for protection in some areas.
The Herring Gull is part of a complex of large gull species that breed throughout the North Temperate zones of North America and Eurasia. The systematic and taxonomic relationships among these species and their subgroups have been the subject of vigorous debate for decades. The North American Herring Gull is currently classified by the American Ornithological Society as a subspecies (Larus argentatus smithsonianus) of a species that also includes two subspecies in northwestern Europe (European Herring Gull, Larus a. argentatus and L. a. argenteus), and another in northeastern Asia and islands in the Bering Sea (Vega Gull, L. a. vegae). Related species breed in western North America (Glaucous-winged Gull L. glaucescens), in Arctic Canada and Greenland (Iceland Gull L. glaucoides and Thayer’s Gull L. thayeri), in northern Europe and western Asia (Lesser Black-backed Gull L. fuscus, now also established as a breeding species in North America), and in southern Europe and south-central Asia (Yellow-legged Gull L. michahellis, Caspian Gull L. cachinnans, and Armenian Gull L. armenicus). Phylogenetic relationships among these species are complicated by fairly frequent hybridization, both within the group and with more distantly-related gull species. Taxonomists in Europe nowadays generally treat the North American and European Herring Gulls as different species, whereas the American Ornithological Society treats them as conspecific (see Systematics). The distinction is important, because there are differences in ecology and behavior that can be confounded if the three subspecies are treated as conspecific.
'Herring Gulls’ have been extensively studied, both in North America and in Europe, and there is a vast scientific literature on them from both areas. This account is focused on what is known of the Herring Gull in North America, relying on European literature mainly for topics on which North American information is sparse or lacking, or where there are indications of possible differences. Much more precise information is needed to be able to compare their behavior and ecology in detail, but ‘Herring Gulls’ are so variable and adaptable that it will be difficult to make rigorous comparisons. Within North America, most studies of the Herring Gull have been conducted at the southern and eastern fringes of their breeding range, in the Great Lakes and along the Atlantic coast from Newfoundland to New Jersey. Virtually nothing is known about the species throughout most of its breeding range: on fresh waters across Canada, including most of the boreal forest. Although most North American Herring Gulls migrate through and spend the winter months in areas with dense human populations, there have been few detailed studies of their ecology in their overwintering quarters.
In this account, citations to named individuals refer to unpublished data supplied as personal communications. Unpublished data from the revisors are cited with initials only (ICTN, DVW, CEH, MLM, AFP, JCE).