Glaucous-winged Gull Larus glaucescens 灰翅鷗
Category I. Accidental in winter.
IDENTIFICATION
May 2009, Michelle and Peter Wong. First-winter.
58-62 cm. Large, strongly-built gull with a stout bill and deep dull pink legs. First year birds are rather uniform pale brown with pale-fringed primaries no darker than rest of bird and have an all-dark bill. As moult occurs darker more greyish feathers appear. As with other northerly gulls, the upperpart feathers are prone to wear and fading in the southerly latitudes of south China. Confusion can occur with pale and bleached first-year Slaty-backed Gull, but on the latter the secondaries and tail are usually darker than the primaries and the outer primaries have darker outer webs imparting a more contrasting pattern.
May 2009, Michelle and Peter Wong. First-winter.
Relatively broad and short wings. On some birds the flight feathers can become extremely bleached and worn in the second half of the winter.
The adult has pale grey upperparts with slightly darker tips to primaries and deep pink legs; in non-breeding plumage has extensive pale brown mottling on head and neck. Second-year birds are uniform rather dirty greyish above with slightly darker primaries, paler underparts and pale uppertail coverts; advanced birds can be obviously grey on the mantle. Third-year birds have largely grey upperparts, white trailing edge to secondaries and pale underparts extensively marked with brownish.
VOCALISATIONS
Similar to other large gulls, though some calls are higher pitched than is typical.
DISTRIBUTION & HABITAT PREFERENCE
All records have occurred in the intertidal areas of Deep Bay.
OCCURRENCE
1993: first-year on 27 February.
1994: first-year on 24 January.
2000: single first-years on 13 January and 30 January.
2009: first-year from 22 March to 31 May.
BEHAVIOUR, FORAGING & DIET
No information.
RANGE & SYSTEMATICS
Monotypic. Breeds in the northern Pacific around the Bering Sea from the Commander Islands and Kamchatka to southwest and south Alaska; winters south of sea ice regularly as far south as Hokkaido, Japan in the west and California in the east Pacific (Hayward and Verbeek 2020). Few records in China but has occurred along the south coast (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend increasing.
Hayward, J. L. and N. A. Verbeek (2020). Glaucous-winged Gull (Larus glaucescens), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.glwgul.01
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.
