White-winged scoter

The white-winged scoter (Melanitta deglandi) is a large sea duck. The genus name is derived from Ancient Greek melas "black" and netta "duck". The species name commemorates French ornithologist Côme Damien Degland.[2]

White-winged scoter
Adult male of the American race deglandi
Female, Toronto

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Melanitta
Subgenus: Melanitta
Species:
M. deglandi
Binomial name
Melanitta deglandi
(Bonaparte, 1850)
Synonyms

Melanitta fusca deglandi

Description

The white-winged scoter is one of three North American scoter species and the largest species of scoter. It is characterised by its bulky shape and large bill. Females range from 950–1,950 g (2.09–4.30 lb) and 48–56 cm (19–22 in), averaging 1,180 g (2.60 lb) and 52.3 cm (20.6 in). She is brown with pale head patches. The male ranges from 1,360–2,128 g (2.998–4.691 lb) and from 53–60 cm (21–24 in), averaging 1,380 g (3.04 lb) and 55 cm (22 in). He is all black, except for white around the eye and a white speculum. This scoter's bill has a black base and a large knob.

White patches are visible but not conspicuous when wings are folded

There are a number of differing characteristics of the Stejneger's scoter and the white-winged scoter. Males of the white-winged scoter have browner flanks, dark yellow coloration of most of the bill and a less tall bill knob, approaching the velvet scoter. Stejneger's scoter has a very tall knob at the base of its mostly orange-yellow bill. Females are identical in the field.

The Latin binomial commemorates the French zoologist Dr. Côme-Damien Degland (1787–1856).

Taxonomy

It was formerly considered to be conspecific with the velvet scoter, and some taxonomists still regard it as so. These two species, the Stejneger's scoter, and the surf scoter, are placed in the subgenus Melanitta, distinct from the subgenus Oidemia, black and common scoters. Stejneger's scoter was suggested to be a full species, according to a new study.[3]

Distribution

The white-winged scoter breeds over the far north of North America. It winters further south in temperate zones, on the Great Lakes, the coasts of the northern United States and the southern coasts of Canada.. It forms large flocks on suitable coastal waters. These are tightly packed, and the birds tend to take off together. It has occurred as a vagrant in Europe, including Scotland,[4] Iceland,[5] Norway and Ireland,[6]

Behavior

Breeding

The lined nest is built on the ground close to the sea, lakes or rivers, in woodland or tundra. 5–11 eggs are laid. The pinkish eggs average 46.9 mm (1.85 in) in breadth, 68.2 mm (2.69 in) in length and 82.4 g (2.91 oz) in weight. The incubation period can range from 25 to 30 days. After about 21 days, neighboring females may start to behave aggressively towards other nesting females, resulting in confusion and mixing of broods. By the time she is done brooding, a female may be tending to as much as 40 offspring due to the mixing from these conflicts. The female will tend to her brood for up to 3 weeks and then abandon them, but the young will usually stay together from another 3 weeks. Flight capacity is thought to be gained at 63 to 77 days of age.

Food

In freshwater, this species primarily feeds on crustaceans and insects; while in saltwater areas, it feeds on molluscs and crustaceans. The favorite foods are an amphipod (Hyalella azteca) in freshwater, and rock clams (Protothaca staminea), Atlantic razor clams (Siliqua spp.), and Arctic wedge clams (Mesodesma arctatus).

References
  1. BirdLife International (2018). "Melanitta deglandi". IUCN Red List of Threatened Species. 2018: e.T22734194A132663794. doi:10.2305/IUCN.UK.2018-2.RLTS.T22734194A132663794.en.
  2. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 132, 246. ISBN 978-1-4081-2501-4.
  3. "Siberian Scoter (Melanitta stejnegeri)".
  4. "Changes to the British List". British Ornithologists' Union. 5 December 2013. Retrieved 23 December 2018.
  5. "American White-winged Scoters in Iceland". The Icelandic Birding Pages. Gunnlaugur Pétursson / Yann Kolbeinsson. Retrieved 23 December 2018.
  6. Martin Garner (2014). "Velvet, White-winged and Stejneger's Scoters: A Photographic Guide" (PDF). Birdwatch. Retrieved 23 December 2018.
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