Smew

Smew
Male (top) and female Smew
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Subfamily:	Merginae
Genus:	Mergellus Selby, 1840
Species:	M. albellus
Binomial name
Mergellus albellus (Linnaeus, 1758)
Synonyms
Mergus albellus

The Smew (Mergellus albellus) is a small duck, which is somewhat intermediate between the typical mergansers (Mergus) and the goldeneyes (Bucephala). It is the only member of the genus Mergellus; sometimes included in Mergus, this genus is distinct (though closely related) and might actually be a bit closer to the goldeneyes.^[1] The Smew has interbred with the Common Goldeneye (B. clangula).

An unnamed fossil seaduck, known from a humerus found in the Middle Miocene Sajóvölgyi Formation (Late Badenian, 13–12 million years ago) of Mátraszõlõs, Hungary, was assigned to Mergus. However, the authors included the Smew therein, and consequently, the bone is more properly assigned to Mergellus—especially as it was more similar to a Smew's than to the Bucephala remains also found at the site. It is sometimes^[2] argued that the Mátraszõlõs fossil is too old to represent any of the modern seaduck genera, but apparently these were all well-distinct even back then.^[3]

The living species is known to exist since about 2 to 1.5 million years, as attested by fossils from the earliest Pleistocene found in England.^[4]

Description

The drake Smew, with its 'cracked ice' appearance, is unmistakable, and looks very black-and-white in flight. The females and immature males are grey birds with chestnut foreheads and crowns, and can be confused at a distance with the Ruddy Duck; they are often known as "redhead" Smew. It has oval white wing-patches in flight. The Smew's bill has a hooked tip and serrated edges, which help it catch fish when it dives for them.

Distribution and ecology

Smew taking off

This species breeds in the northern taiga of Europe and Asia. It needs trees for breeding. The Smew lives on fish-rich lakes and slow rivers. As a migrant it leaves its breeding areas and winters on sheltered coasts or inland lakes of the Baltic Sea, the Black Sea, northern Germany and the Low Countries, with small number reaching Great Britain (for example, at Dungeness), mostly at regular sites. Vagrants have been recorded in North America. On lakes it prefers areas around the edges, often under small trees.

The Smew breeds in May and lays 6–9 cream-colored eggs. It nests in tree holes, such as old woodpecker nests. It is a shy bird and flushes easily when disturbed.

The Smew is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. It is not considered threatened by the IUCN.^[5]

Footnotes

1. ^ Livezey (1986)
2. ^ E.g. Mlíkovský (2002): p.123
3. ^ Gál et al. (1998-99)
4. ^ Mlíkovský (2002): p.123
5. ^ BLI (2004)

References

• BirdLife International (BLI) (2004). Mergellus albellus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006., Database entry includes justification for why this species is of least concern
• Gál, Erika; Hír, János; Kessler, Eugén & Kókay, József (1998–99): Középsõ-miocén õsmaradványok, a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból. I. A Mátraszõlõs 1. lelõhely [Middle Miocene fossils from the sections at the Rákóczi chapel at Mátraszőlős. Locality Mátraszõlõs I.]. Folia Historico Naturalia Musei Matraensis 23: 33-78. [Hungarian with English abstract] PDF fulltext
• Livezey, Bradley C. (1986): A phylogenetic analysis of recent anseriform genera using morphological characters. Auk 103(4): 737-754. PDF fulltext DjVu fulltext
• Mlíkovský, Jirí (2002): Cenozoic Birds of the World, Part 1: Europe. Ninox Press, Prague. ISBN 80-901105-3-8 PDF fulltext

External links

• Smew videos, photos & sounds on the Internet Bird Collection