Melanitta nigra

Geographic Range

Common scoters breed from Iceland, the British Isles, and Norway east to Russia and Siberia. Their range extends to the lower Khantanga drainage and down to the Kamchatka Peninsula. Common scoters winter primarily in the Baltic and North Sea area from northern Norway south along the coast to Portugal and out to sea as far as the Azores. They may winter south to Japan, Korea, and occasionally eastern China (Bordage and Savard 2011).

• Biogeographic Regions
• palearctic palearctic
  • native native

Habitat

Common scoters are typically found on open salt water, rarely being found inland (Sibley 2012). They may use freshwater lakes during migration but will moult and overwinter at sea (Birdlife International 2012). They prefer lakes less than 10 ha that are relatively shallow with a gross till or rock substrate (Bordage and Savard 2011). Melanitta nigra is restricted to water less than 20 m deep because they dive while feeding. Optimally the water is 5 to 15 m with abundant benthic fauna (Birdlife International 2012; Kaiser et al. 2006). Inhabited lakes are usually saturated in oxygen, clear, acidic (pH greater than 5), low conductivity, with little emergent vegetation (Bordage and Savard 2011). These waters may be shallow inshore waters that are typically between 500 m and 2 km from shore.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• coastal coastal

Physical Description

Common scoters are the smallest, most compact of the scoters with relatively small bills and rounded heads (Sibley 2012). Adult males are solid black except for a butter-colored swelling at the base of the bill. Male common scoters have a total length of 49 cm with a mass of 1100 g, while females are 45 cm in length and weigh 980 g. Females are dark brown with a pale cheek and a dark crown (Bordage and Savare 2011). The underwings of common scoters are completely dark and unpatterned. However, adult males have a completely black upperwing, while adult females and immature black scoters have a dark brown upperwing (Carney 1992). Immature birds resemble the female but are more mottled with white on the breast and belly. New hatchlings are dark brown or sooty black on the back that gradually fade to light grey underneath. (Bordage and Savare 2011).

Since 2010, common scoters (previously Melanitta nigra nigra ) and black scoters (previously Melanitta nigra americana ) have been considered distinct species instead of having subspecies status under the name Melanitta nigra . This decision was largely based on vocal calls, but bill shape, amount of yellow pigment in the bill, and nostril shape varies as well (Sangster et al. 2005).

Adult males can easily be separated from other scoters by the pattern and shape of the bill (Bordage and Savard 2011). When looking at the wings, common scoters can be distinguished from relatives by the 10th primary being shorter than the 9th primary. The 10th primary is either black and attenuated or gray-black and tapering but in either case, it is much narrower than the 9th primary. In oldsquaw’s , the 9th primary is the longest with the outerweb of this feather narrowing near the tip. Surf scoters 10th primary is the longest, but all primaries are uniformly tapering (Carney 1992).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently

Reproduction

Common scoter pair formation likely occurs upon arrival on wintering grounds during late fall and winter. However, courtship activity also occurs in the spring. There is usually a single female with several males in courting groups. Males will display with an upward stretch of the head, tail snap, forward rush, water flicked by the bill, a breast-preen, forward stretch, erect, and then a head shake. Occasionally they may ignore the tail snap and rushes. Other movements that males might exhibit during their display include an upper shake, a short flight, underwater preening, wing flaps, and steaming (something like a short, airless flight. During this time, the female is often aggressive toward the male and will rush him in turn. Females will show their preference by head stretch posture and calling. In addition, they will show aggression to all other males (Bordage and Savard 2011).

Common scoters appear to be monogamous. However, forced copulation events may occur. Pre-copulatory displays may include mock-preening by both sexes. Males will exhibit a single upward shake while females assume a prone posture. She is then mounted immediately. Post-copulation, the male will swim away displaying a tail snap, low rush, and upward shake. The female then bathes (Bordage and Savard 2011).

• Mating System
• monogamous monogamous

It is assumed that common scoters breed for the first time at two or more years of age but it is poorly studied (Bordage and Savard 2011). Melanitta nigra arrives at breeding grounds between late-April and May but breed from late-May to June in solitary pairs. After June, males migrate to inshore or to offshore coastal waters for their flightless moult (Birdlife International 2012). Nests hatching occurs at this time. However, this time varies depending on weather conditions (Bordage and Savard 2011). Females and young remain at these breeding grounds until September. This breeding ground is often boggy tundra or Arctic dwarf heath on pools, small lakes, streams, and slow rivers with low banks. Often these areas have a high abundance of prey (Birdlife International 2012).

Common scoters build nests that are a scrape on the ground hidden by vegetation and is either close to water or in dwarf heath (Birdlife International 2012). Eggs are elliptical to oval and are pale pinkish-buff, off-white, or ivory. They are approximately 64.16 by 44.62 mm in size with an average thickness of 0.315 mm. Melanitta nigra usually has a clutch size of 8 to 9 eggs, laying them in a 1 to 2 day interval. Replacement clutches have been documented but with fewer eggs. In addition, nest parasitism occurs sometimes (Bordage and Savard 2011).

Females incubate eggs for 30 to 31 days in the wild and a reported 27 to 28 days for captive birds (Bordage and Savard 2011). Young are precocial, covered fully in down with eyes open. Often they will leave the nest as soon as the down is dry. They weigh about 43 g at birth and between day 1 and 18 weigh an average of 316.7 g. Young between 19 and 42 days weigh an average of 511.5 g (Bordage and Savard 2011).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Females create nests in a depression in the ground and line them with grass and down. There they lay eggs in a one to two day interval, where the male will remain with the female until the clutch is complete. Females then incubate the eggs after the last eggs are laid. Nest attentiveness has not been well studied with common scoters, but it is believed that at least two hours are spend off the nest and feeding on the adjacent lake. In the first week, the female will occasionally brood the nest and she will actively watch over her brood for 1 to 3 weeks. These broods are often abandoned before they can even fly and they begin feeding themselves upon reaching water shortly after hatching (Bordage and Savard 2011).

• Parental Investment
• precocial precocial
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

There is little data on the lifespan of common scoters. However, a study of recaptures in White Sea suggests a mean annual mortality of 20% with a maximum life expectancy of 8 years after banding that is probably underestimated due to poor-quality rings. Recovery of banded birds in Iceland suggest that annual adult survival of scoters is 0.77 ± 0.04 (Bordage and Savard 2011). It is suggested that the maximum lifespan of Melanitta nigra in the wild is 16.8 years (AnAge, 2012).

Behavior

This species is not known to be territorial beyond a male defending the moving space around a female during breeding season. Physical interaction occurs mostly in courting parties but they tend to sleep in tight flocks on the water. During the day, they spend most of their time feeding and will form small groups to do so. If other species intrude, then males or females will rush as a threat display. This is usually faster than the rush in courtship displays (Bordage and Savard 2011).

Three types of dives have been described in this species: using feet only, using feet for propulsion and half-extended wings for "planes or rudders", and using both feet and half-extended wings for propulsion. Often wing-flaps with a downward thrust of the head can be seen while swimming. Mass synchronized dives have been observed (Bordage and Savard 2011). In addition, common scoters are highly gregarious during non-mating seasons, having large flocks from several hundred to a thousand though over 100,000 individuals have been seen during the winter (Birdlife International 2011).

• Key Behaviors
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• social social

Home Range

Home range size is not reported in common scoters.

Communication and Perception

Common scoters use vocalizations and body language (such as posture and movement) to communicate. Females give a low hoarse call while males give a slurred, plaintive, whistled "peeew" (Sibley 2012). The vocal repertoire of these birds appears to be small, but they are the most vocal of the scoters (Bordage and Savard 2011).

The most commonly heard vocalization is the male courtship call (Sangster 2009). There is clear diagnostic differences in the male courtship call of Melanitta nigra and Melanitta americana ; however, there is no diagnostic difference across various distributions of the two species. The call of Melanitta americana is much longer than the call of Melanitta nigra though they are both single notes that differ in midpoint frequency. This varied vocalization is what led to the understanding that these are separate species. Vocalizations play a role in pair formation and pair bonding in scoters (Sangster et al. 2005, Sangster 2009). The call of a courting male is a mellow whistle, while females emit a low growl (Bordage and Savard 2011).

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Common scoters are a type of diving duck that feeds on prey species that live within the upper substratum of the water. Their diet is mostly composed of bivalve mollusks with crabs, small fish, and gastropods also included. Echinoderms have been found in their diet at such a low quantity that it is presumed to be accidental intake (Kaister et al. 2006). Along the Belgian coasts it was found that 47% of the of the diet was composed of polychaetes , 20% was bivalves , 14% was amphipod crustaceans , 6% was decapod crustaceans , with the remaining in various taxa (Degraer et al. 1999). Up to 10% of Melanitta nigra diet might be composed of plants (Bordage and Savard 2011). Melanitta nigra tends to be highly aggregated and, as such, severely diminish food resources in an area over the season. While the mechanism for feeding is unknown, most do not consider them visual feeders (Kaiser et al. 2006).

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
  • molluscivore molluscivore
  • eats other marine invertebrates

• Animal Foods
• fish
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• echinoderms

• Plant Foods
• algae

Predation

Little is known about predation on Melanitta nigra and few studies have looked into this. In Iceland, gyrfalcons will prey on adults. Eggs and young are taken by ravens and minks (Bordage and Savard 2011).

Ecosystem Roles

Common scoters prey upon mollusks, crustaceans, worms, echinoderms, isopods, amphidods, insects, and small fish and may locally impact populations of these prey (BirdLife International 2012). Like most birds, they are susceptible to parasites. Jennings and Soulsby (2009) found Tetrameres fissispina , Echinuria horrida , Polymorphus minutus , Amidostomum anseris , and Spilotrema pygmaeum in common scoters. In black scoters it was found that females had more "freshwater" parasites than males, conversely males carried more "marine" parasites than females (Bordage and Savard 2011). This might be similar to common scoters, considering that they share similar life histories.

Economic Importance for Humans: Positive

Humans hunt common scoters in some regions and eggs have been harvested in Iceland and some countries in Europe (Gudmundsson 1979, Kaiser et at. 2006).

• Positive Impacts
• food food

Economic Importance for Humans: Negative

There are no known adverse effects of common scoters on humans. They compete at small, local scales with humans for some benthic shellfish but these are not significant economic impacts (BirdLife International 2012).

Conservation Status

Common scoters are identified as least concern according to the IUCN Red List due an extremely large range with a large population. However this species is adversely affected by oil spills, chronic oil pollution, human disturbance, and the degradation of food resources from oil exploration, and coastal habitat destruction. Populations wintering off coasts of western Europe are threatened from offshore wind farming and some breeding habitats are being negatively affected by eutrophication (BirdLife International 2012). Common scoters are protected in the United Kingdom under the Wildlife and Countryside Act of 1981 as amended and through the Countryside and Rights of Way Act in 2000. This controls hunting and provides protection against disturbances for breeding birds (Kaiser et al. 2006).

Additional Links

Encyclopedia of Life

Contributors

Rebekah Spicer (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Banks, A., W. Sanderson, B. Hughes, P. Cranswick, L. Smith, S. Whitehead, A. Musgrove, B. Haycock, N. Fairney. 2008. The Sea Empress oil spill (Wales, UK): effects on common scoter Melanitta nigra in Carmarthen Bay and status ten years later. Marine Pollution Bulletin , 56/5: 895-902.

Bengtson, S. 1971. Habitat selection of duck broods in Lake Mývatn area, north-east Iceland. Ornis Scandinavica , 2/1: 17-26.

BirdLife International, 2012. " Melanitta nigra " (On-line). IUCN Red List of Threatened Species. Accessed April 16, 2013 at http://www.iucnredlist.org/details/139494910/0 .

Bordage, D., J. Savard. 2011. "Black Scoter" (On-line). The Birds of North America.

Bourgeois, C., W. Threlfall. 1982. Metazoan parasites of three species of scoter (Anatidae). Canadian Journal of Zoology , 60/10: 2253-2257.

Carney, S. 1992. Species, age and sex identification of ducks using wing plumage . Washington D.C.: U.S. Department of the Interior, U.S. Fish and Wildlife Service. Accessed January 21, 2013 at http://www4.ncsu.edu/~csdepern/documents/WaterfowlWings.pdf .

Degraer, S., M. Vincx, P. Meire, H. Offringa. 1999. The macrozoobenthos of an important wintering area of the common scoter ( Melanitta nigra ). Journal of the Marine Biological Association of the UK , 79/2: 243-251.

Fox, A., Æ. Petersen, M. Frederiksen. 2003. Annual survival and site-fidelity of breeding female common scoter Melanitta nigra at Myvatn, Iceland, 1925-1958. Ibis , 145/2: E94-E96.

Fox, A., P. Hartmann, I. Petersen. 2008. Changes in body mass and organ size during remigial moult in common scoter Melanitta nigra . Journal of Avian Biology , 39/1: 35-40.

Gudmundsson, F. 1979. The Past Status and Exploitation of the Mývatn Waterfowl Populations. Oikos , 32: 232-249.

Jennings, A., J. Soulsby. 2009. Diseases of Wild Birds, Fourth Report. Bird Study , 4/4: 216-220.

Kaiser, M., M. Galanidi, D. Showler, A. Elliott, R. Caldow, E. Rees, R. Stillman, W. Sutherland. 2006. Distribution and behavior of common scoter Melanitta nigra relative to prey resources and environmental parameters. Ibis , 148: 110-128.

Kuhnlein, H., D. Appavoo, N. Morrison, R. Soueida, P. Pierrot. 1994. Use and nutrient composition of traditional Sahtú (Hareskin) Dene/Métis foods. Journal of Food Composition and Analysis , 7/3: 144-157.

Sangster, G., J. Collinson, A. Helbig, A. Knox, D. Parkin. 2005. Taxonomic recommendations for British birds: third report. Ibis , 147: 821-826.

Sangster, G. 2009. Acoustic differences between the scoters Melanitta nigra nigra and M.n. americana . The Wilson Journal of Ornithology , 121/4: 696-702.

Sibley, D. 2012. The Sibley field guid to birds of eastern North America . New York: Andrew Stewart Publishing Inc.

2012. "AnAge" (On-line). Human Aging Genomic Resources. Accessed April 16, 2013 at http://genomics.senescence.info/species/entry.php?species=Melanitta_nigra .

2013. "IOC World Bird List" (On-line). Accessed February 14, 2013 at http://www.worldbirdnames.org/n-waterfowl.html .

2013. "The British List" (On-line). British Ornithologists’ Union. Accessed February 14, 2013 at http://www.bou.org.uk/british-list/ .

2013. "Waterbird Population Estimates" (On-line). Wetlands International. Accessed February 14, 2013 at http://wpe.wetlands.org/view/2374 .