Black Scoter Melanitta americana 黑海番鴨
Category I. Accidental.
IDENTIFICATION
Dec. 2007, Martin Hale.
45-49 cm. Stocky, short-necked and medium-sized duck. Adult males are all dark without white in wing and have a large bright swollen orange-yellow knob at the base of the upper mandible. Females are dark brown above with dark cap upward from the level of the eye reaching to the hind neck and a contrastingly pale lower half to face. On both sexes the underwing coverts are very dark and contrast with the paler greyish undersides of the flight feathers.
Although both are all black at rest, separation from male Common Scoter M. nigra is relatively straightforward due to the latter’s lack of a swollen orange-yellow bill knob. Females are more difficult, but according to Garner (2008) Black Scoter differs in having a swollen base and more prominent nail on the bill, a steeper forehead and squarer head shape, a square cut or broad rounded lower border to the dark cap, cleaner cheeks with a less obvious dark vertical cheek mark and darker on the sides of the nape.
VOCALISATIONS
Both on and away from the breeding grounds males have been recorded giving a plaintive or mournful but rather low-pitched whistle. The female can give a croaking call.
OCCURRENCE
The sole record is of a first-winter at Mai Po NR on 9 December 2007 (Smith and Allcock 2011).
BEHAVIOUR, FORAGING & DIET
The bird at Mai Po NR spent most of its time roosting and swimming among a flock of Tufted Ducks. While swimming it sat higher in the water and continuously held its tail cocked in the manner of a ‘stiff-tail’ duck. It regularly flapped its wings, raising its body while thrusting its head low over the water (Smith and Allcock 2011).
RANGE & SYSTEMATICS
Monotypic. In North America there are two disjunct breeding populations: in western Alaska and northern Quebec (Bordage and Savard 2020). In east Asia it breeds in the tundra regions of eastern Siberia from Yana River east to Kamchatka (Madge and Burn 1988). Winters along western and eastern Pacific coastal areas, including Japan. In China has been recorded off the east coast of Shanghai and Fujian, as well as inland in southern Jiangsu and Chongqing (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Near-threatened. Population in moderately rapid decline due to various threats.
Bordage, D. and J.-P. L. Savard (2020). Black Scoter (Melanitta americana), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blksco2.01
Garner, M. (2008). Frontiers in Birding. Birdguides Limited, U.K.
Madge, S. and H. Burn (1988). Wildfowl. An identification guide to the ducks, geese and swans of the world. Christopher Helm, Kent, U.K.
Smith, B. and J. Allcock (2011). Black Scoter Melanitta americana at Mai Po. The first Hong Kong record. Hong Kong Bird Report 2007-08: 202-206.
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.
