Slender-Billed Gull Chroicocephalus genei 細嘴鷗
Category I. Accidental in winter to coastal areas, mainly in Deep Bay.
IDENTIFICATION
Mar. 2010, Michelle and Peter Wong. Adult, breeding plumage.
42-44 cm. Similar to Black-headed Gull. Structurally distinct due to smaller head, longer forehead, bill, legs and, when extended, neck; usually has a pale iris. Lacks a dark hood in breeding plumage (illustrated), when it usually has a pinkish wash to the underparts and a darker red bill and legs. Has only faint ear spot in winter.
Oct. 2016, Kinni Ho. First calendar-year.
First-year birds have paler bill and legs than Black-headed Gull, in addition to some brown median coverts and a dark tip to the tail.
Oct. 2016, Kinni Ho.
On first-year birds the secondaries are paler, the leading edge of wing is white and the brown on wing coverts usually paler and more restricted than on Black-headed Gull.
VOCALISATIONS
Similar to Black-headed Gull but slightly lower-pitched and more nasal or throaty on average.
DISTRIBUTION & HABITAT PREFERENCE
All birds have occurred in intertidal areas, mainly Deep Bay, with one also seen at roost on Mai Po NR. The first record was seen both in Deep Bay and at Starling Inlet.
OCCURRENCE
1990: adult in Deep Bay on 10 February and at Starling Inlet during 25-26 February (Kennerley and Hoogendoorn 1991).
1992: first-summer irregularly at Mai Po and in Deep Bay during 3-10 April.
1993: adult in Deep Bay during 27-28 February.
2008: first-winter in Deep Bay during 1-21 March and on 13 April.
2010: adult in Deep Bay from 7 February to 9 March.
2016: first-winter in Deep Bay during 24-30 October.
BEHAVIOUR, FORAGING & DIET
No information.
RANGE & SYSTEMATICS
Monotypic. Breeds in scattered areas from southwest Spain east through the Mediterranean, Black and Caspian Seas to Kazakhstan, where it is most numerous; winters coastally in nearby areas as well as west Africa, the Arabian Peninsula and western India (Burger et al. 2020). In China it is a rare migrant through Xinjiang and the east coast, with small numbers occurring in winter along the south coast, including Taiwan (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend unknown.
Burger, J., M. Gochfeld, and E. F. J. Garcia (2020). Slender-billed Gull (Chroicocephalus genei), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.slbgul1.01
Kennerley, P. R. and W. (T.) Hoogendoorn (1991). Slender-billed Gull at Mai Po and Starling Inlet: the first record for Hong Kong. Hong Kong Bird Report 1990: 100-102.
Liu, Y. and Y. H. Chen (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
