- Aythya marila
Identification
Length 40–50 cm, wingspan 70–80 cm, weight 900–1250 g
A medium sized diving duck, very slightly smaller than Common Pochard (much overlap), but distinctly larger than Tufted Duck.
Male easily identified by the rounded head which is a glossy green-black and lacks a tuft. The eye is yellow and the bill pale grey with small black 'nail'. Lower throat and upper chest area black, as is the rump and vent area. Flanks and belly white with fine vermiculations on the back, these appearing greyish white at long range.
Eclipse male and first-winter male appear browner than the breeding males, more like females, with a pale patch to the base of the bill. The white flanks take on a muddied appearance.
Female shares the rounded head shape and yellow eye, and with a white area at the base of the bill which can be quite large. In spring and summer most birds also have a pale area on the ear-coverts. The overall colouring is a dull, often slightly rufous-brown with slightly paler flanks. At very close range the vermiculations on the back of the female can be made out.
Similar Species
Tufted Duck, Lesser Scaup and Common Pochard. The Lesser Scaup is essentially identical in all plumages, but the head shape is slightly different, with a peak behind the eye instead of on the forehead with a hint of a short stubby crest, a smaller black spot on the bill's 'nail', and in males, coarser vermiculation on the grey mantle. In flight, the white wingbar is only on the secondaries, grey on the primaries. The bill in the Greater is also longer and wider. These differences can be quite difficult to discern, so range and habitat are often better determinates.
Distribution
Holarctic. Breeds across the far north of Europe and Asia (Iceland, and across northern Scandinavia and Russia), and northern North America (Alaska and northern Canada). Migratory, wintering off sheltered sea coasts and on larger freshwater lakes close to the limit of frozen waters; in Europe mostly in Scandinavia but some south to Ireland, Britain, the Alps (Lake Geneva, Bodensee, etc.) and the Black and Caspian Seas; in Asia mainly off the coasts of Japan, Korea, and eastern China; and in North America on the Great Lakes and along coasts south to roughly the USA - Mexico border. Males tend to winter further north than females.
Taxonomy
Two subspecies are recognised[1]
- A. m. marila – northern Eurasia
- A. m. nearctica – northern North America - Male more coarsely marked dorsally.
Note: Some sources[2] consider birds breeding and wintering in East Asia to be A. m. nearctica, but Banks has shown that they are actually nominate marila[7].
Habitat
Prefers salt water along the coast in winter, but also uses larger freshwater lakes. In summer, breeds on tundra lakes and pools.
Behaviour
Diet
Omnivorous; their main diet consists of molluscs. In the past, large flocks also gathered to feed on spent grain left after brewing beer and dumped at sea in the Firth of Forth in Scotland, but pollution control measures have stopped this food resource.
Breeding
Starts May to early June, mainly mid May in Fennoscandia and Northern Russia, and from late May in Iceland. Seasonally monogamous. Pairs or loose groups. Nest is a depression lined with grass and down, on ground, often in thick vegetation. Usually 8-11 eggs, larger clutches indicate occasional egg dumping.
Vocalisation
Listen to Greater Scaup voice clip
References
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2018. The eBird/Clements checklist of birds of the world: v2018. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
- Gill, F & D Donsker (Eds). 2018. IOC World Bird List (v8.2). doi : 10.14344/IOC.ML.8.2. Available at http://www.worldbirdnames.org/
- Carboneras, C. & Kirwan, G.M. (2018). Greater Scaup (Aythya marila). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/52912 on 2 October 2018).
- Kessel, B., D. A. Rocque, and J. S. Barclay (2002). Greater Scaup (Aythya marila), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.650
- Madge, S. & Burn, H. (1988) Waterfowl. An identification guide to the ducks, geese and swans of the world. Houghton Mufflin, Boston.
- Todd, F. (1979). Waterfowl. Ducks, Geese & Swans of the World. Sea World, San Diego.
- Banks, R.C. (1986). "Subspecies of the Greater Scaup and their names" Wilson Bulletin. 98 (3): 433–444.
Recommended Citation
- BirdForum Opus contributors. (2024) Greater Scaup. In: BirdForum, the forum for wild birds and birding. Retrieved 20 April 2024 from https://www.birdforum.net/opus/Greater_Scaup
External Links
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