Brown-headed Gull Chroicocephalus brunnicephalus Scientific name definitions

41–45 cm; 450–714 g; wingspan 105–115 cm. Two-year gull. Larger, stockier and flatter-crowned than L. ridibundus, with which it is often found in winter. Solid black wingtip  characteristic in all plumages (1 Olsen, K. M., and H. Larsson (2003). Gulls of Europe, Asia and North America. Christopher Helm, London, UK. Close ). Distinguished by wingtip pattern , recalling that of L. delawarensis, very different from L. ridibundus and L. maculipennis, which have largely white outer primaries; in adults the broad white primary bases contrast with the grey upperwing and black wingtip. Breeding adult has the hood  pale brown, becoming blackish at nape, forming an indistinct collar reminiscent of L. cirrocephalus; narrow white eye-crescents towards rear; mantle, back and inner part of wing grey, outer wing-coverts white; primaries white at base, broadly black distally, with white windows on outermost two; bill bright red, with dusky tip; legs bright to dark red; iris pale yellow or greyish, with narrow red orbital ring. Non-breeding adult has pale grey head with grey-brown marks around eye, on ear-coverts, and often over crown; in winter crown becomes pale grey, cheeks and throat white. Immature   resembles young L. ridibundus, but has solid black primaries with white bases; underwing grey; bill yellowish with dusky tip; legs orange.

• Slender-billed x Brown-headed Gull (hybrid) Chroicocephalus genei x brunnicephalus

Mountains of SC Asia, between 3000 m and at least 4500 m: Turkestan and W China (W Xinjiang), and S to Pamirs (L Kara-Kul), Ladakh and Tibet. Winters on coasts of India, N Sri Lanka and SE Asia, sparingly W to Arabian Peninsula.

Breeds on islands in large, cold, high altitude lakes of varying salinity, or in adjacent marshes, mainly on the Tibetan plateau at 3000–4000 m. Outside the breeding season it frequents coasts, coastal wetlands, estuaries and rivers, often in flocks of hundreds (1 Olsen, K. M., and H. Larsson (2003). Gulls of Europe, Asia and North America. Christopher Helm, London, UK. Close ).

Migrates over mountains to coasts of S Asia; fairly common in Nepal, where some remain to winter. Known to migrate through Hebei, Shanxi and Inner Mongolia also to India , Gulf of Thailand and SE Asia, where often common close inshore and inland. Abundant in winter on L Sambhar (Rajasthan). Less numerous on large rivers.

Fish, shrimps, offal; also insects, grubs, slugs, earthworms, sewage, potatoes, rodents and plant shoots; occasionally winged termites. Fish, where present, form main diet. On L Kara-Kul, where there are few fish, feeds mainly on invertebrates, particularly adult caddisflies (Astratus alaicus) and amphipods. In winter, associates with fishing boats and consumes refuse. Often feeds in shallow water, by immersing head and neck. Catches termites by aerial hawking.

A raucous  “keear” or “geek”, deeper and gruffer than in Black-headed Gull. Also a loud, wailing “ko-yek ko-yek” (2 Grimmett, R., C. Inskipp, and T. Inskipp (1998). Birds of the Indian Subcontinent. Christopher Helm, London, UK. Close , 3 MacKinnon, J. R., and K. Phillipps (2000). A Field Guide to the Birds of China. Oxford University Press, Oxford, UK. Close ).

Returns to colonies in May; lays from end of May, mainly in early Jun, even when lakes still frozen. Colonies of c. 50 pairs, but reports of several thousand pairs (Tibet); often near Common Terns Sterna hirundo. Nests usually close together, made of masses of plant stems; large, bulky nests built in marshes, smaller nests on land. Usually three eggs (1–4, mean 2·4 in Pamirs); incubation and fledging periods unknown (former possibly c. 24 days); chick very pale grey, spotted dark above; mean hatching weight c. 33 g; brooded for most of time up to c. 10th day, only at night until 14th. Even older young may perish in heavy overnight frosts. One record of hybridisation with Larus genei (4 Limparungpatthanaki, W. (2012). Hybridisation between Brown-headed Gull Larus brunnicephalus and Slender-billed Gull Larus genei in the Inner Gulf of Thailand. BirdingASIA. 18 : 86–89. Close ).

Not globally threatened (Least Concern). Global population not known with any precision but the species seems to be quite numerous; a provisional estimate suggests 100,000–200,000 individuals (5 Wetlands International (2015). Waterbird Population Estimates. Wetlands International, Wageningen, The Netherlands. Close ). Little studied but a survey of 48 high-altitude lakes on Changtang Plateau, N Tibet, during Jul–Aug 2008 found the species on 31 lakes, with a total of 11,621 birds, including 5000 birds on the saline L Dong (6 Zhang Guo-gang, Liu Dong-ping, Jiang Hong-xing, Zhang Ke-jia, Zhao Huai-dong, Kang Ai-li, Liang Hai-tang, and Qian Fa-wen (2015). Abundance and conservation of waterbirds breeding on the Changtang Plateau, Tibet Autonomous Region, China. Waterbirds. 38(1): 19–29. Close ). There is a record of  c. 1000 pairs found nesting in the Pamirs (Tadjikistan). In winter, large flocks of several hundred or more are noted in many parts of India and SE Asia; common in Sri Lanka. Some 6000–7000 winter annually on inner Gulf of Thailand (4 Limparungpatthanaki, W. (2012). Hybridisation between Brown-headed Gull Larus brunnicephalus and Slender-billed Gull Larus genei in the Inner Gulf of Thailand. BirdingASIA. 18 : 86–89. Close ).