Black-legged Kittiwake Rissa tridactyla 三趾鷗
Category I. Rare visitor in late winter and spring.
IDENTIFICATION
Apr. 2008, Michelle and Peter Wong. First-winter.
38-41 cm. Medium-sized rather elegant gull with relatively narrow wings and short legs. Birds in first-winter plumage have a distinctive blackish M-pattern on the grey upperwings.
Adults have medium grey upperparts and cleanly demarcated black wing tips (apart from black outer web to outermost primary visible at close range) with no mirrors; in winter plumage acquires a dark ear spot and dusky hindneck. Bill is yellow, duller in winter; legs are black.
VOCALISATIONS
The flight call is a short ‘kow’ that falls in pitch slightly.
DISTRIBUTION AND HABITAT PREFERENCE
Has either been recorded at sea, mainly in southern waters, or roosting with other gulls in the intertidal area of Deep Bay.
OCCURRENCE
Since the first record on 20 February 1975 (Viney 1976), Black-legged Kittiwake has been recorded on average in one out of two years; however, most records have occurred in the period 2006 to 2014. All have occurred in the second half of the winter and spring from 13 January to 19 April and on 22 May. Since 2006 observer activity in southern waters, especially around Po Toi, has become more intense, and this is responsible for many of the records. There have been no records since 2014, however.
BEHAVIOUR, FORAGING & DIET
No information.
RANGE & SYSTEMATICS
Has a circumpolar breeding distribution on coasts and islands, with concentrations from Novaya Zemlya to the New Siberian Islands, around the Sea of Okhotsk, western Alaska and Greenland. Winters pelagically in both Atlantic and Pacific south to the Tropic of Cancer, though nearly reaches equator in eastern Atlantic. In China recorded around the coast, with occasional records inland (Liu and Chen 2020).
Two subspecies are recognised, of which R. t. pollicaris breeds from east Siberia to west Alaska and winters in the Pacific, including HK.
CONSERVATION STATUS
IUCN: VULNERABLE. Population decreasing rapidly over past three generations, and likely to be continuing. Climate change related decreases in prey abundance are thought to the cause.
Hatch, S. A., G. J. Robertson, and P. H. Baird (2020). Black-legged Kittiwake (Rissa tridactyla), 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.bklkit.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.
Viney, C. A. (1976). Systematic List for 1975. Hong Kong Bird Report 1975: 7-43.
