Laridae

Laridae is a family of seabirds in the order Charadriiformes that includes the gulls, terns and skimmers. It includes around 100 species arranged into 22 genera. They are an adaptable group of mostly aerial birds found worldwide.

Taxonomy
The family Laridae was introduced (as Laridia) by the French polymath Constantine Samuel Rafinesque in 1815. Historically, Laridae were restricted to the gulls, while the terns were placed in a separate family, Sternidae, and the skimmers in a third family, Rynchopidae. The noddies were traditionally included in Sternidae. In 1990 Charles Sibley and Jon Ahlquist included auks and skuas in a broader family Laridae.

A molecular phylogenetic study by Baker and colleagues published in 2007 found that the noddies in the genus Anous formed a sister group to a clade containing the gulls, skimmers and the other terns. To create a monophyletic family group, Laridae was expanded to include the genera that had previously been in Sternidae and Rynchopidae.

Baker and colleagues found that the Laridae lineage diverged from a lineage that gave rise to both the skuas (Stercorariidae) and auks (Alcidae) before the end of the Cretaceous in the age of dinosaurs. They also found that the Laridae themselves began expanding in the early Paleocene, around 60 million years ago. The German palaeontologist Gerald Mayr has questioned the validity of these early dates and suggested that inappropriate fossils were used in calibrating the molecular data. The earliest charadriiform fossils date only from the late Eocene, around 35 million years ago.

Anders Ödeen and colleagues investigated the development of ultraviolet vision in shorebirds, by looking for the SWS1 opsin gene in various species; as gulls were the only shorebirds known to have developed the trait. They discovered that the gene was present in the gull, skimmer and noddy lineages but not the tern lineage. They also recovered the noddies as an early lineage, though the evidence was not strong.

The genera are listed in taxonomic order.

Genus Anous
(5 species)
 * Brown Noddy or Common Noddy, Anous stolidus
 * Black Noddy, Anous minutus
 * Lesser Noddy, Anous tenuirostris
 * Blue-grey Noddy / Blue Noddy, Anous cerulea
 * Grey Noddy, Anous albivitta

Genus Creagrus

 * Swallow-tailed Gull, Creagrus furcatus

Genus Rissa
Kittiwakes (2 species)
 * Black-legged Kittiwake, Rissa tridactyla
 * Red-legged Kittiwake, Rissa brevirostris

Genus Pagophila

 * Ivory Gull, Pagophila eburnea

Genus Xema

 * Sabine's Gull, Xema sabini

Genus Chroicocephalus
(13 species, including 1 extinct)
 * †Huahine Gull, Chroicocephalus utunui
 * Slender-billed Gull, Chroicocephalus genei
 * Bonaparte's Gull, Chroicocephalus philadelphia
 * Black-headed Gull, Chroicocephalus ridibundus
 * Brown-headed Gull, Chroicocephalus brunnicephalus
 * Andean Gull, Chroicocephalus serranus
 * Brown-hooded Gull, Chroicocephalus maculipennis
 * Grey-hooded Gull, Chroicocephalus poiocephalus
 * Grey-headed Gull, Chroicocephalus cirrocephalus
 * Hartlaub's Gull, Chroicocephalus hartlaubii
 * Black-billed Gull, Chroicocephalus bulleri
 * Red-billed Gull, Chroicocephalus scopulinus
 * Silver Gull, Chroicocephalus novaehollandiae

Genus Saundersilarus

 * Saunders's Gull, Saundersilarus saundersi

Genus Hydrocoloeus

 * Little Gull, Hydrocoloeus minutus

Genus Rhodostethia

 * Ross's Gull, Rhodostethia rosea

Genus Leucophaeus
(5 species)
 * Dolphin Gull, Leucophaeus scoresbii
 * Grey Gull, Leucophaeus modestus
 * Lava Gull, Leucophaeus fuliginosus
 * Laughing Gull, Leucophaeus atricilla
 * Franklin's Gull, Leucophaeus pipixcan

Genus Ichthyaetus
(6 species)
 * White-eyed Gull, Ichthyaetus leucophthalmus
 * Sooty Gull, Ichthyaetus hemprichii
 * Great Black-headed (or Pallas's) Gull, Ichthyaetus ichthyaetus
 * Audouin's Gull, Ichthyaetus audouinii
 * Mediterranean Gull, Ichthyaetus melanocephalus
 * Relict Gull, Ichthyaetus relictus

Genus Larus
(25 species)
 * Pacific Gull, Larus pacificus
 * Belcher's Gull, Larus belcheri
 * Olrog's Gull, Larus atlanticus
 * Black-tailed Gull, Larus crassirostris
 * Heermann's Gull, Larus heermanni
 * Common Gull / Mew Gull, Larus canus
 * Ring-billed Gull, Larus delawarensis
 * Western Gull, Larus occidentalis
 * Yellow-footed Gull, Larus livens
 * Great Black-backed Gull, Larus marinus
 * European Herring Gull, Larus argentatus
 * Armenian Gull, Larus armenicus
 * Yellow-legged Gull, Larus michahellis
 * Caspian Gull, Larus cachinnans
 * Kelp Gull, Larus dominicanus (called "Southern Black-backed Gull" or "Karoro" in New Zealand)
 * Cape Gull, Larus dominicanus vetula
 * Lesser Black-backed Gull, Larus fuscus
 * Heuglin's Gull, Larus heuglini
 * California Gull, Larus californicus
 * American Herring Gull, Larus smithsonianus
 * Glaucous-winged Gull, Larus glaucescens
 * Glaucous Gull, Larus hyperboreus
 * Iceland Gull, Larus glaucoides
 * Thayer's Gull, Larus glaucoides thayeri
 * Kumlien's Gull, Larus glaucoides kumlieni
 * Slaty-backed Gull, Larus schistisagus
 * Vega Gull / East Siberian Herring Gull, Larus vegae
 * Mongolian Gull, Larus mongolicus

Distribution and habitat
The Laridae have spread around the world, and their adaptability has likely been a factor. Most have become much more aerial than their ancestor, which was likely some form of shorebird.