Surf scoter

In 1750 the English naturalist George Edwards included an illustration and a description of the surf scoter in the third volume of his A Natural History of Uncommon Birds. He used the English name "The great black duck from Hudson's Bay". Edwards based his hand-coloured etching on a preserved specimen that had been brought to London from the Hudson Bay area of Canada by James Isham. When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition, he placed the surf scoter with the ducks and geese in the genus Anas. Linnaeus included a brief description, coined the binomial name Anas perspicillata and cited Edwards' work. The surf scoter is now one of six species placed in the genus Melanitta that was introduced by the German zoologist Friedrich Boie in 1822. The genus name Melanitta combines the Ancient Greek meaning "black" and meaning "duck". The specific name is from the Modern Latin meaning "spectacled", in turn derived from "to see through". A cladistic analysis based on several morphological characters placed the surf scoter as a monotypic taxon, closest to the white-winged scoter (Melanitta deglandi) and the velvet scoter (Melanitta fusca), which are both sister taxa. These three species form the subgenus Melanitta, distinct from the subgenus Oidemia, which contains the black scoter (Melanitta americana) and the common scoter (Melanitta nigra). The genus Melanitta is part of the Mergini tribe, a monophyletic group of the Northern Hemisphere. This tribe is part of the family Anatidae, along with the swans and geese. == Description ==

The surf scoter reaches sexual maturity after 3 years. The adult male is on average 1,050 g (2.31 lb) and 48 cm (19 in) in length while the adult female averages about 900 g (2.0 lb) and 44 cm (17 in) in length, making this the smallest species of scoter on average. The surf scoter has a wingspan of 29.9–30.3 in (76–77 cm). The male is completely velvety black except for white patches on the forehead and the nape. It has a swollen bill, appearing orange at a distance but patterned with white, red and yellow, and a black spot near the base. The female is browner than the male, with a fairly uniform plumage, slightly darker above than below. Indistinct paler patches are present on the cheeks below the eye and sometimes a whitish patch is on the nape, a unique trait among scoters. The bill is black with green or blue colorations The juvenile has a plumage similar to the female, but mainly paler and browner, and the breast and belly are whitish. The surf scoter is easily distinguishable from other scoters by the white patch on the head of the adult male and its unique bill pattern. Females and immatures have a bulkier bill with a squarish base and a more flattened head profile than other scoters. The black and the white-winged scoters are physically very similar to the surf scoter but in flight, the surf scoter is the only one with completely dark wings. The plumage is a good indicator of the age for male surf scoters, but not for females. Second-year males are similar to adults but may have brownish feathers and/or lack the white forehead patch. Vocalization Surf scoters are generally silent and their few vocalizations are poorly known. During courtship display, males perform a gurgling call and an explosive puk-puk. Females defend their young with a crowlike call. When alarmed, surf scoters will often make a sound like a "guk", somewhere between a "cluck" and a "tok", while rapidly surveying their environment or taking to flight en masse. == Distribution and habitat==

Compared to most Northern American sea ducks, the surf scoter breeds exclusively in North America, mostly in Northern Canada and Alaska. This migratory species breeds in the boreal forests near northern freshwater lakes. The departure date of the birds may vary according to their wintering site, but the date of arrival and settling on the nesting site appear to be synchronous. This suggest that because of different factors such as the weather or varied foraging conditions, the individuals adjust their migration timing to meet an optimized reproductive schedule. The ducks face very different environmental conditions depending on the location of their wintering grounds, which affect their migratory behavior. Higher proportions of males have been located in the northern part while more females and juveniles winter in the southernmost portion of the range. In spring, males and females migrate together to their breeding area and they usually settle at their nesting sites less than a week after arrival. == Behavior ==

Breeding Surf scoters form pairs on wintering and staging grounds. Most pairs are formed before the arrival on the breeding grounds. Studies showed a strong fidelity in the nesting areas of surf scoters over the years. The building of the nest usually starts in mid-May to early June and it occurs on the ground close to the sea, lakes or rivers, in woodland or tundra. Females dig a bowl-shaped nest in the ground and lines it with nearby ground debris and down. About 5 to 9 eggs are laid and each may range from 55 to 79 g (1.9–2.8 oz) and average 43.9 mm (1.73 in) in breadth and 62.4 mm (2.46 in) in length. The incubation lasts for about 28 to 30 days and is provided by the female only. When they reach those food-rich wetland, they begin feeding on their own. The mother abandons its young before they reach the flight age, at about 55 days. For example, they start feeding in seagrass beds, on epifaunal crustaceans that have increased in size over winter or on Pacific herring eggs (Clupea pallasi), during the fish spawning. As the prey landscape changes, surf scoters will adjust their foraging effort and habitat selection. Effort is lowest in December, due to high prey abundance, and it increases until mid-February, when prey declines. It increases again in March, probably due to the increasing daylight time for foraging. As the season progresses, surf scoters move to habitats with lower prey declines, instead of staying in habitats poor in prey and increasing their foraging effort. A surf scoter usually captures its food underwater and consumes it whole. They have been observed to select smaller bivalves than those available, probably because of the energy cost of processing shell matter. They also seem to select slow-swimming epifaunal crustaceans. Flocks of surf scoter appear to dive in a highly synchronous fashion and this synchrony is correlated with the group size. Dive duration vary with many factors such as prey type, density and profitability, season Predation of eggs and ducklings have not been studied in detail but bald eagles, golden eagles and mustelids have been identified as the main predators of surf scoters in marine habitats. Marked individuals showed a higher mortality rate in winter than during wing molt. In November, 2007, an oil spill in San Francisco harbour oiled and killed thousands of birds including many surf scoters. About 40% of the birds affected were from this species. Scientists said that while the species is not endangered it has declined 50–70% over the past 40 years and this spill could decrease populations since most of the affected birds are healthy adults. == Status ==

The extremely large range and population size of the surf scoter assures it a status of Least Concerned, according to the IUCN. The populations have been apparently decreasing over the last years, but this small decline is not rapid enough to consider moving the species in the Vulnerable category. The global population is estimated to be between 250,000 and 1,300,000 individuals. ==References==