Laridae

Laridae
Name	Laridae
Taxon	Laridae
Authority	Rafinesque, 1815
Subdivision ranks	Genera
Subdivision	* Larus * Ichthyaetus * Leucophaeus * Chroicocephalus * Hydrocoloeus * Rhodostethia * Xema * Rissa * Pagophila * Creagrus

Laridae. The family Laridae encompasses the gulls, terns, and skimmers, a globally distributed and highly recognizable group of seabirds. These birds are a common sight along coastlines, inland waterways, and even urban environments, known for their opportunistic feeding strategies and often raucous behavior. Their evolutionary success is marked by considerable adaptability, with species inhabiting environments from the high Arctic to tropical coral reefs and major inland cities like London and Chicago.

Taxonomy and systematics

The classification within Laridae has undergone significant revision with the advent of molecular phylogenetics. Historically, gulls, terns, and skimmers were often placed in separate families, but genetic studies, including those published in journals like The Auk, support their grouping as subfamilies: Larinae (gulls), Sterninae (terns), and Rynchopinae (skimmers). Key genera of gulls include the large white-headed gulls of the genus Larus, such as the European Herring Gull, and smaller hooded gulls like those in Chroicocephalus. Terns are primarily classified under the genus Sterna, exemplified by the Common Tern, while the distinctive Black Skimmer is the sole New World representative of the genus Rynchops. The work of ornithologists like Edward H. Burtt Jr. has been instrumental in understanding their complex relationships.

Description and characteristics

Larids exhibit a range of sizes, from the small Little Gull to the large Great Black-backed Gull. Most species have long, pointed wings, webbed feet, and stout, slightly hooked bills. Plumage is typically white with varying shades of gray or black on the wings and back; many gulls, like the Franklin's Gull, develop a dark hood during the breeding season. Terns are generally more slender and graceful than gulls, with longer, pointed bills and often forked tails, as seen in the Arctic Tern. The Black Skimmer possesses a unique bill adaptation where the lower mandible is longer than the upper, an adaptation for its specialized feeding method. Juveniles of many species, such as the Ring-billed Gull, have mottled brown plumage that gradually matures over several years.

Distribution and habitat

Members of this family are found on every continent, including Antarctica, where the Snow Petrel shares the skies with the South Polar Skua, a close relative. They are supremely adaptable to aquatic habitats, occupying coastal shorelines, estuaries, salt marshes, sandbars, and inland lakes and rivers. Some species, like the Kelp Gull, are common around the Southern Ocean, while others, such as the Ivory Gull, are highly specialized for life in the high Arctic pack ice. Several species have become highly synanthropic, thriving in human-altered landscapes including harbors, landfills, and agricultural fields near cities like San Francisco and Sydney.

Behavior and ecology

Larids are predominantly carnivorous and highly opportunistic. Gulls are notorious scavengers, feeding on fish, invertebrates, carrion, and human refuse, a behavior famously studied by Niko Tinbergen. Terns are more specialized, primarily plunge-diving for small fish, as demonstrated by the Royal Tern. The Black Skimmer employs a unique technique, flying low and skimming the water's surface with its lower mandible to catch prey. Most species are colonial nesters, with breeding colonies often located on isolated islands like the Farne Islands or Midway Atoll to avoid predators. They are known for vigorous defense of their nests, with species like the Arctic Tern famously dive-bombing intruders. Many undertake remarkable migrations; the Arctic Tern makes the longest known migration, traveling from its Arctic breeding grounds to the Antarctic Circle.

Relationship with humans

The relationship between larids and humans is complex and multifaceted. Gulls, in particular, are both cherished and considered pests. They are iconic symbols of the seaside in places like Brighton and Coney Island, but their adaptability has led to conflicts, such as at airports like Heathrow Airport where they pose bird-strike risks. They have been subjects of cultural significance, appearing in literature like Jonathan Livingston Seagull by Richard Bach and in the films of Alfred Hitchcock. Historically, the eggs of species like the Black-headed Gull were collected for food in places like The Wash in England. Their role as indicators of marine ecosystem health is critical for scientists monitoring pollution in areas like the North Sea and Chesapeake Bay.

Conservation status

Conservation status varies widely across the family. While many gull species are common and even increasing due to human subsidy, several tern and skimmer species face significant threats. The Chinese Crested Tern is critically endangered, with a tiny population threatened by egg collection and habitat loss. The Black Skimmer is listed as endangered in several U.S. states due to coastal development and disturbance. Conservation efforts are often focused on protecting breeding colonies from predation by invasive species like rats and foxes on islands, and managing human disturbance. International agreements like the Agreement on the Conservation of African-Eurasian Migratory Waterbirds provide frameworks for their protection across range states.

Category:Charadriiformes Category:Bird families