This small, black-hooded gull nests in colonies of up to 25,000 pairs on sandy or rocky shores and on salt-marsh islands along the Atlantic and Gulf coasts of North America, as well as on some Caribbean islands, the Gulf of California, and along the Pacific coast of Mexico. Its light, buoyant flight and lilting, laughing call are a familiar sight and sound on these coasts. This species has adapted well to the presence of humans, gathering around picnic groups for handouts, following fishing boats, or waiting about docks for fishermen. For many people along the Atlantic and Gulf coasts, the laughing call and delicate head tosses of this lovely gull are harbingers of spring. In mid-April pairs touch down on sandy beaches or salt-marsh wrack to begin courtship, their dark gray mantles silky and soft, their vibrant black heads gleaming in the sun, their dark eyes ringed with narrow white eye-crescents, and their exaggerated head tosses and graceful Facing-away Displays a courtship dance all their own.
This gull is susceptible to human disturbance and predation throughout its breeding cycle. It avoids mammalian predators by selecting small islands exposed to winter washovers that prevent establishment of permanent mammal populations. Colony and nest-site selection is a compromise between nesting on islands high enough to avoid tidal flooding and small and low enough to avoid predation and competition with larger gulls.
After an extensive period of postbreeding wandering up and down the coast, East Coast Laughing Gulls migrate south down the Atlantic and Gulf coasts to South America; Pacific Coast breeders disperse northward to the Salton Sea in southern California and migrate south to winter from southern Mexico to Peru. Here the birds seek habitats similar to those chosen on their breeding grounds—harbors, estuaries, and coastal lagoons. Many remain in the southern United States during the winter, feeding on fish, crustaceans, worms, carrion, and garbage.
Extirpated from many coastal colonies in the late 1800s and early 1900s by eggers and the millinery trade, the Laughing Gull expanded its range and numbers early in the 20th century only to be devastated later by competition with larger gulls expanding their range southward. Today the Laughing Gull is increasing in much of its range, and indeed is the most abundant breeding seabird along the U.S. East Coast, Maine to Florida. Numbers can change rapidly. There and elsewhere, it has adapted to feeding on landfills and mowed fields surrounding airports, posing a hazard to aircraft. As a result, this species has been managed (culled) near large airports such as John F. Kennedy in New York City. And management (culling of eggs and adults) is ongoing near breeding colonies of endangered terns on islands in the Gulf of Maine.
Formerly placed in the genus Larus, along with other gulls, the Laughing Gull is now found in the genus Leucophaeus. As constituted for many decades, the genus Larus included most of the world's gull species but a recent molecular study found that small, hooded or dark-headed gulls, as well as the kittiwakes and various monotypic species, are in lineages relatively distinct from the lineage of the large, white-headed gulls (Pons et al. 2005). Relationships within Leucophaeus are unclear. Laughing Gull is often considered closest to L. pipixcan (Franklin's Gull), although a study by Pons et al. (2005) using a limited genetic sample of species in this genus, placed L. atricilla sister to a clade of L. pipixcan + L. fuliginosus (the Lava Gull of the Galapagos Is.), and a cladistic analysis of skeletal and integumentary characters (Chu 1998) failed to resolve the genus as now recognized.