Saunders's Gull Saundersilarus saundersi Scientific name definitions

29–32 cm; 170–220 g; wingspan 87–91 cm. Two-year gull. Intermediate in size and shape between Hydrocoleus minutus and L. ridibundus. Breeding adult has head  and nape black , with white crescents  above and below rear of eye; back and upperwing-coverts blue-grey; outer primaries white, tipped black; inner primaries mainly black, forming diagnostic black patch  on underwing beyond “wrist”; secondaries mainly white; bill black; legs and feet reddish; iris dark brown. Non-breeding adult  has white head  , with grey marks on neck and black spot before and behind eye. Superficially similar to H. minutus, but larger, with different upperwing and underwing patterns. Wing pattern similar to that of L. ridibundus, but differs in short, heavy, slightly hooked, black bill. Resembles L. philadelphia, but has disproportionately heavy bill. First-winter wing pattern resembles L. ridibundus but head and heavy bill recall H. minutus. The black tail bar is very narrow (1 Olsen, K. M., and H. Larsson (2003). Gulls of Europe, Asia and North America. Christopher Helm, London, UK. Close ).

Coastal E China from Liaoning through Hebei and Shandong to Jiangsu; sporadically on W coast of Korea (2 Moores, N. (1998). Saunders’s Gull colony in South Korea: first nesting record outside of People’s Republic of China. Oriental Bird Club Bull. 28: 43. Close ). Winters from S Korea and S Japan S to N Vietnam (3 Cao, L., M. A. Barter, and X. Wang (2008). Saunders’s Gull: a new population estimate. Bird Conservation International 18(4): 301–306. Close ).

Mainly found along coast, occasionally on bodies of fresh water near coast. Breeds at coastal saltmarshes and river deltas, rather than at inland lakes as originally reported. Winters on coastal mudflats.

Birds move S & E off coast of E China, and in winter recorded in North and South Korea, N Kyushu in S Japan; rare elsewhere in Japan (4 Shimba, T. (2007). A Photographic Guide to the Birds of Japan and North-East Asia. Christopher Helm, London. Close ), and from E China and Taiwan to Hong Kong, Hainan and N Vietnam, with a single recent (Jan/Feb 2015) record in Philippines (Luzon) (5 Robson, C., S. Roddis, M. Sykes, and B. Sykes (2015). From the field. BirdingASIA 23:138–144. Close ). A recent assessment of the wintering population found birds in E & S China (9625 individuals from Jiangsu S), Hong Kong (China) (35), Macau (China), Taiwan (China) (700), along W & S coasts of South Korea (2000 individuals), in SW Japan (2000) and in Vietnam (c. 10) (3 Cao, L., M. A. Barter, and X. Wang (2008). Saunders’s Gull: a new population estimate. Bird Conservation International 18(4): 301–306. Close ).

Little known but thought to be a dietary specialist that exploits silt-laden estuarine waters especially rich in small crabs  , e.g. Macrophthalmus abbreviatus, which it dismembers with its strong bill; it also takes small fish and polychaete worms (6 Brazil, M. (1992). The threatened Saunders' Gull of East Asia. Birding World. 5: 72–74. Close ), with a study in Hong Kong reporting that the latter constituted 94% of identified prey among adults and 67% for first-winters. Feeding activity is especially synchronised with the tides, ebb tides providing the most productive conditions (7 Yoon J., Yoon H-J., Go B-G., Joo E-J. and Park S-R. (2013). Tide associated incubation and foraging behaviour of Saunders’s Gulls Larus saundersi. Ardea. 101: 99–104. Close ).

Gives harsh, tern-like, calls “kip” and also “chao” (1 Olsen, K. M., and H. Larsson (2003). Gulls of Europe, Asia and North America. Christopher Helm, London, UK. Close ).

Little-known. All known colonies are in coastal saltmarshes, in areas of the ecotone dominated by Suaeda glauca. Nest a shallow cup lined with Suaeda twigs. Clutch size normally three eggs (1–6); clutches of 5–6 eggs suggest female-female pairing. Birds arrive at Shuangtai Hekou National Nature Reserve, NE China, as early as mid Mar and begin displaying during late Apr. Colonies are established by early May when incubation begins. Chicks hatch during late May and the first juveniles fledge in late Jun (6 Brazil, M. (1992). The threatened Saunders' Gull of East Asia. Birding World. 5: 72–74. Close ).

VULNERABLE. Previously listed as Endangered. In 1990s, total population estimated at fewer than 5000, and probably closer to 3000 individuals, and all seven known colony sites were either being developed or planned for development for agriculture or aquaculture (particularly for shrimps); in 2008, however, the availability of recent counts from key non-breeding regions permitted the population to be re-estimated at a minimum of 14,400 birds (3 Cao, L., M. A. Barter, and X. Wang (2008). Saunders’s Gull: a new population estimate. Bird Conservation International 18(4): 301–306. Close ). The breeding grounds of this poorly known species were not discovered until 1984 (8 Shi Zerong, Thouless, C.R. and Melville, D.S. (1988). Discovery of the breeding grounds of Saunders’ Gull Larus saundersi. Ibis. 130(3): 445-446. Close ). It breeds in four Chinese provinces: Liaoning, with c. 600–700 pairs; Hebei, with c. 25 pairs; Shandong, with c. 200 pairs at two colonies; and Jiangsu, with 300–750 pairs at two colonies. Breeding is also reported sporadically in South Korea; in 2011–2012 there was a single colony of 200–300 pairs, at Incheon (7 Yoon J., Yoon H-J., Go B-G., Joo E-J. and Park S-R. (2013). Tide associated incubation and foraging behaviour of Saunders’s Gulls Larus saundersi. Ardea. 101: 99–104. Close ). The principal threat is reclamation of tidal flats and saltmarshes External link , Suaeda glauca habitat being also threatened by the expansion of the introduced Spartina alterniflora (9 Jiang, H.X., Hou, Y.Q., Chu, G.Z., Qian, F.W., Wang, H., Zhang, G.G. and Zheng, G.M. (2010). Breeding population dynamics and habitat transition of Saunders's Gull Larus saundersi in Yancheng National Nature Reserve, China. Bird Conservation International. 20(1): 13–24. Close ). Oil exploration also destroys the species’ saltmarsh habitat and displaces the gulls. Fishermen collect eggs for food. Delayed breeding subjects vulnerable young to late-summer typhoons. Colonies are close to fishing villages, and frequent human disturbance causes low reproductive success or even desertion. Coastal cities are undergoing industrial development, and this contributes to pollution from coastal sewage and industrial waste. Female-female pairs possibly a consequence of contamination by chemical agents.