The Herring Gull, perhaps the most common and familiar gull of the northeastern United States and western Europe, is a large white-headed gull that inhabits shorelines of oceans, seas, lakes, and large rivers. Its circumboreal breeding range includes much of Europe and Central Asia. In North America it breeds along the Atlantic Coast from Cape Hatteras north to Davis Strait and Baffin Island and throughout arctic Canada into eastern Alaska. In winter, North American Herring Gulls may be found throughout their breeding range and south into tropical waters, primarily along coastlines in southern Florida, Central America and Baja California, and the Gulf of Mexico.
This species been divided into at least nine subspecies, of which only one, L. a. smithsonianus, breeds in North America. Several Asiatic subspecies have recently been accorded tentative species status. Herring Gulls hybridize in zones of sympatry with several other large white-headed gulls, including Glaucous-winged (L. glaucescens) and Lesser Black-backed (L. fuscus) gulls, and new species may have arisen through hybridization in this group in Asia.
The behavior and ecology of the Herring Gull are well studied, especially in Europe and Canada. Although this species is an opportunistic feeder, most individuals feed primarily on natural prey such as marine fishes and invertebrates. Studies from Europe and North America indicate that individual gulls specialize in their foraging and that choice of diet influences breeding performance. This species generally nests in colonies, often large ones; successful nesting appears to require sites near water and safe from terrestrial predation, sites such as islands, offshore rocks, or abandoned piers. This gull typically lays three-egg clutches in May, which generate fledged offspring by mid- to late July.
Nearly extirpated by plumage hunters and eggers in North America during the nineteenth century, the Herring Gull has recovered its numbers owing to protection. By the 1960s, North American populations may even have exceeded historical numbers, possibly the result of plentiful food derived from human refuse. Numbers in New England stabilized during the 1970s. In recent years this species has expanded its range south into Maryland, Virginia, and North Carolina, but it has also been largely displaced from certain breeding habitats in New England by the Great Black-backed Gull (L. marinus).