Black scoter

Black scoter
Adult male
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Superorder: Galloanserae
Order: Anseriformes
Family: Anatidae
Subfamily: Merginae
Genus: Melanitta
Subgenus: (Oidemia)
Species: M. americana
Binomial name
Melanitta americana
(Swainson, 1832)
Synonyms

Melanitta nigra americana

The black scoter or American scoter (Melanitta americana) is a large sea duck, 43 to 49 cm (17 to 19 in) in length. Together with the common scoter M. nigra, it forms the subgenus Oidemia; the two are sometimes considered conspecific, the black scoter then being referred to as M. nigra americana. Its French name, used in parts of its Canadian range, is macreuse noire (also meaning "black scoter").[2] The species is listed as Near Threatened by the IUCN.

Description

The adult female averages about 980 g (2.16 lb) and 45 cm (18 in) in length, while the adult male is on average 1,100 g (2.4 lb) and 49 cm (19 in) in length. It is characterised by its bulky shape and large bill. The male is all black with a very bulbous bill which is mostly yellow. The female is a brown bird with pale cheeks, very similar to female common scoter.

This species can be distinguished from other scoters, apart from common scoter, by the lack of white anywhere on the drake, and the more extensive pale areas on the female.

Standard Measurements[3][4]
length 430–550 mm (17–21.5 in)
weight 950 g (2.09 lb)
wingspan 710 mm (28 in)
wing 213–233 mm (8.4–9.2 in)
tail 83–97 mm (3.3–3.8 in)
culmen 42–45.5 mm (1.65–1.79 in)
tarsus 45–48.5 mm (1.77–1.91 in)

Vocalisations

Black scoter and common scoter have diagnosably distinct vocalisations.[5]

Distribution and habitat

The black scoter breeds in the far north of North America in Labrador and Newfoundland to the southeast Hudson Bay. It also occurs on the Siberian side of the Bering Straits east of the Yana River. It winters farther south in temperate zones, on the coasts of the northern USA and Canada, on the Pacific coast south to the San Francisco Bay region and on the Atlantic and Gulf of Mexico coasts, and in Asia as far south as China.[2][6]

Some birds may over-winter on the Great Lakes. This species is a very rare vagrant to western Europe; only drakes are safely identifiable out of range, so females are likely to be undetected.

Ecology

This species dives for crustaceans and molluscs while migrating or wintering on the sea-coasts, and feeds on insects and their larvae, especially caddisflies, fish eggs and, more rarely, vegetation such as duck weed while nesting on freshwater. It forms large flocks on suitable coastal waters in winter quarters. These are tightly packed, and the birds tend to take off together; in the breeding season they are less social. It has been suggested that in coastal waters this species prefers sheltered embayments, and possibly waters that include some mixed depths.[7]

The lined nest is built on the ground close to the sea, lakes or rivers, in woodland or tundra. 5–7 eggs are laid. Each eggs weighs from 60–74 g (2.1–2.6 oz), or 8% of the females body weight. The incubation period may range from 27 to 31 days. Females brood their young extensively for about 3 weeks, after which the still flightless young must fend for themselves.

The male performs a diagnostic downward head movement when stretching his wings.[4]

References

  1. ↑ BirdLife International (2013). "Melanitta americana". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. 1 2 "Black Scoter (Melanitta nigra)". Sea Duck Information Series. Sea Duck Joint Venture. 2003. Retrieved October 2003.
  3. ↑ Godfrey, W. Earl (1966). The Birds of Canada. Ottawa: National Museum of Canada. p. 358.
  4. 1 2 Sibley, David Allen (2000). The Sibley Guide to Birds. New York: Knopf. p. 98. ISBN 0-679-45122-6.
  5. ↑ Sangster, George (2009). "Acoustic Differences between the Scoters Melanitta nigra nigra and M. n. americana". The Wilson Journal of Ornithology 121 (4): 696–702. doi:10.1676/04-088.1.
  6. ↑ Some unusual records for San Mateo County, California. Abstract in: Littlejohn, Chase (1916). "Minutes of Cooper Club Meetings". Condor 18 (1): 38–40. doi:10.2307/1362896.
  7. ↑ Deghi, Gary; et al. (1998). Environmental Impact Report for the Pillar Point East Harbor Master Plan (Report). San Mateo County Harbor District: Earth Metrics Inc.

Further reading

External links

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