The Pallas's Gull or Great Black-headed Gull, Ichthyaetus ichthyaetus, is a large gull

Gull

Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

. As is the case with many gulls, it has traditionally been placed in the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Larus

Larus

Larus is a large genus of gulls with worldwide distribution . Many of its species are abundant and well-known birds in their ranges...

.

This species breeds in colonies in marshes and islands from southern Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 to Mongolia

Mongolia

Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

. It is migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, wintering in the eastern Mediterranean, Arabia

Arabian Peninsula

The Arabian Peninsula is a land mass situated north-east of Africa. Also known as Arabia or the Arabian subcontinent, it is the world's largest peninsula and covers 3,237,500 km2...

 and India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. This gull nests on the ground, laying between two and four eggs.

It occurs in western Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 only as a rare vagrant. In Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 a recent review left a single occurrence in 1859 as the only acceptable record of this bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

.
This is a very large gull, nearly the size of the largest (the Great Black-backed Gull

Great Black-backed Gull

The Great Black-backed Gull is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic...

), and it is easily the world's largest black-headed gull. It measures 58–70 cm (22.8–27.6 in) in length with a 1.4 to 1.7 m (4.6 to 5.6 ft) wingspan. Weight can vary from 0.96–2.1 kg (2.1–4.6 lb), with an average of 1.6 kg (3.5 lb) in males and 1.22 kg (2.7 lb) in females. Summer adults are unmistakable, since no other gull of this size has a black hood. The adults have grey wings and back, with conspicuous white "mirrors" at the wing tips. The legs are yellow and the bill is red.

In all other plumages, a dark mask through the eye indicates the vestiges of the hood. The call is a deep aargh cry. Young birds attain largely grey upperparts quite rapidly, but they take four years to reach maturity.

These birds are predatory, taking fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s and even small mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s.

The Pallas's Gull is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA

AEWA

The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...

) applies.