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Black Scoter Melanitta americana

Justification
This newly split species is listed as Near Threatened on the basis that it is suspected to be undergoing a moderately rapid population decline owing to a number of widespread threats.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Livezey, B. C. 1995. Phylogeny and evolutionary ecology of modern seaducks (Anatidae: Mergini). Condor 97(1): 233-255.

Distribution and population
Melanitta americana breeds in western Alaska (USA), Newfoundland (Canada) and far-eastern Russia (e.g. Collinson et al. 2006). It winters at sea off north-east America, and in the Pacific on the coasts of North America, Russia, Japan, Korea and eastern China (del Hoyo et al. 1992).

Population justification
The total population is estimated to number c.530,000-830,000 individuals (Delany and Scott 2006), probably including c.350,000-560,000 mature individuals, on the basis that they probably account for around 2/3 of the population.

Trend justification
This species is thought to be declining in western Alaska and to be stable on the Arctic coastal plain (per Sea Duck Joint Venture 2003). Numbers also appear to be declining in the Atlantic flyway, whereas no statistically significant population trend is apparent in the results of a fixed-wing aerial survey covering the Atlantic coast for the period 1991-1999 (Sea Duck Joint Venture 2003). Data from the U.S. Fish and Wildlife Service-Canadian Wildlife Service breeding waterfowl survey indicate that the combined population of all three scoter species along survey transects in the western boreal forest may have declined by as much as 75% since the 1950s (Sea Duck Joint Venture 2003). Estimates from a relatively new survey indicate that the breeding population in western Alaska is currently c.160,000 birds and appears to have increased slightly since the survey was initiated in 2004 (R. Stehn per T. Bowman in litt. 2012). Mid-winter inventory data do not indicate any trends on the Pacific coast and only weakly show a decline on the Atlantic coast. However, these surveys are said to track scoter populations poorly and all three species are combined in one count (Sea Duck Joint Venture 2003). An analysis of Christmas Bird Count (CBC) data overall indicates an annual change of -1.26% between 1965-1966 and 2005-2006 across about half of the species’s range in North America (Butcher and Niven 2007), equating to a 40-year decline of c.50%, and thus suggestive of a c.32% decline over the last three generations, estimated to be 23 years, based on a generation length of c.7.5 years (BirdLife International unpubl. data), and the assumption of an exponential trend. However, CBC data are probably unreliable for tracking trends in this species because it winters predominantly offshore, where a large proportion of birds may not be visible to shore-based observers. Trends are apparently uncertain in far north-east Asia, where the species occurs east of Lena and numbers an estimated 300,000-500,000 birds or 12-24% of the estimated global population (see Delany and Scott 2006), thus more research is required. Limited data and anecdotal evidence from South Korea suggests that the species has declined substantially as a wintering species since the 1960s and 1970s (N. Moores in litt. 2012). On the basis of this mixed evidence, the population is suspected to be undergoing a moderately rapid decline (i.e. 20-29% over three generations).

Ecology

Behaviour This species is strongly migratory (del Hoyo et al. 1992) and often travels considerable distances over land making brief stop-overs on inland waters (Madge and Burn 1988). It arrives on its breeding grounds between late-April and May and breeds from late-May onwards (Madge and Burn 1988) in highly dispersed (Kear 2005) solitary pairs (del Hoyo et al. 1992). After mating (from June onwards) males migrate long distances prior to their flightless moult, most travelling in small groups to inshore or offshore coastal waters (Madge and Burn 1988). Females and juveniles leave the breeding grounds in September (Madge and Burn 1988). The species is highly gregarious when not breeding (Madge and Burn 1988) with males forming large congregations during the flightless moulting period (Kear 2005) and large flocks of several hundred to a thousand (Snow and Perrins 1998) or occasionally over 100,000 individuals occurring during winter (Scott and Rose 1996). Non-breeders often oversummer on the wintering grounds (Madge and Burn 1988). Habitat Breeding The species breeds on Arctic dwarf heath (Snow and Perrins 1998, Kear 2005) or boggy tundra on pools, small lakes, streams (del Hoyo et al. 1992) and slow-flowing rivers (Snow and Perrins 1998). It shows a preference for freshwater habitats (del Hoyo et al. 1992) with low banks (Flint et al. 1984), small islets (Kear 2005) and high abundances of aquatic invertebrate and plant life positioned in swampy valleys or among mossy bogs (Flint et al. 1984), especially where suitable shrubs (e.g. willow or birch) and herbaceous vegetation are available for nesting cover (Johnsgard 1978, Snow and Perrins 1998, Kear 2005). It generally avoids areas with steep slopes or wetlands enclosed by forest (Kear 2005). Non-breeding Although the species may use freshwater lakes on migration (Madge and Burn 1988, Kear 2005) the majority moult and overwinter at sea (Kear 2005) on shallow inshore waters less than 20 m deep (Kear 2005) (optimally 5-15 m) (Scott and Rose 1996) with abundant benthic fauna (Kear 2005), generally between 500 m and c.2 km from the shore (Snow and Perrins 1998). Diet Its diet consists predominantly of molluscs, especially during the winter (del Hoyo et al. 1992), although it occasionally takes other aquatic invertebrates such as crustaceans (del Hoyo et al. 1992) (e.g. barnacles and shrimps) (Johnsgard 1978), worms (del Hoyo et al. 1992), echinoderms, isopods, amphidods (Kear 2005) and insects (del Hoyo et al. 1992) (e.g. midges and caddisflies) as well as small fish (del Hoyo et al. 1992) and fish eggs (Snow and Perrins 1998). On the breeding grounds the species may also consume plant matter (del Hoyo et al. 1992) such as seeds, roots and tubers (del Hoyo et al. 1992) and the vegetative parts of aquatic plants (Flint et al. 1984). Breeding site The nest is a scrape on the ground hidden amongst vegetation (del Hoyo et al. 1992) close to water (Madge and Burn 1988, Kear 2005) or placed further away in dwarf heath (Kear 2005).



Threats
The large concentrations of this species that occur during the moulting period and in winter are highly vulnerable to oil spills, chronic oil pollution, human disturbance and the degradation of food resources as a result of oil exploration (Gorski et al. 1977, Nikolaeva et al. 2006). The species also suffers disturbance from high-speed ferries (Larsen and Laubek 2005). The effects of commercial exploitation of benthic shellfish also poses a threat (through competition for food resources) (Kear 2005), and the species's breeding habitats are threatened by eutrophication in some areas (Kear 2005). The species is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006).


Conservation Actions Underway
No targeted conservation actions are known for this species, although it receives monitoring in parts of its range and occurs in some protected areas.

Conservation Actions Proposed
Improve monitoring surveys in order to obtain reliable baseline data and monitor future trends. Assess the significance of various threats. Tighten controls on marine pollution. Increase the area of suitable habitat that receives protection.

References
Butcher, G. S.; Niven, D. K. 2007. Combining data from the Christmas bird count and the breeding bird survey to determine the continental status and trends of North American birds.

Collinson, M.; Parkin, D. T.; Knox, A. G.; Sangster, G.; Helbig, A.J. 2006. Species limits within the genus Melanitta, the scoters. British Birds 99: 183-201.

del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

Flint, V. E.; Boehme, R. L.; Kostin, Y. V.; Kuznetsov, A. A. 1984. A field guide to birds of the USSR. Princeton University Press, Princeton, New Jersey.

Gorski, W.; Jakuczun, B.; Nitecki, C.; Petryna, A. 1977. Investigation of oil pollution on the Polish Baltic coast in 1974-1975. Przeglad Zoologiczny 21(1): 20-23.

Johnsgard, P. A. 1978. Ducks, geese and swans of the World. University of Nebraska Press, Lincoln and London.

Kear, J. 2005. Ducks, geese and swans volume 2: species accounts (Cairina to Mergus). Oxford University Press, Oxford, U.K.

Larsen, J. K.; Laubek, B. 2005. Disturbance effects of high-speed ferries on wintering sea ducks. Wildfowl 55: 99-116.

Madge, S.; Burn, H. 1988. Wildfowl. Christopher Helm, London.

Melville, D. S.; Shortridge, K. F. 2006. Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.

Nikolaeva, N. G.; Spiridonov, V. A.; Krasnov, Y. V. 2006. Existing and proposed marine protected areas and their relevance for seabird conservation: a case study in the Barents Sea region. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 743-749. The Stationary Office, Edinburgh, UK.

Scott, D. A.; Rose, P. M. 1996. Atlas of Anatidae populations in Africa and western Eurasia. Wetlands International, Wageningen, Netherlands.

Sea Duck Joint Venture. 2003. Species status report.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Malpas, L., Taylor, J.

Contributors
Bowman, T., Moores, N., Pihl, S.

Recommended citation
BirdLife International (2014) Species factsheet: Melanitta americana. Downloaded from http://www.birdlife.org on 01/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 01/11/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Near Threatened
Family Anatidae (Ducks, Geese, Swans)
Species name author (Swainson, 1832)
Population size 350000-560000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 3,670,000 km2
Country endemic? No
Links to further information
- Additional Information on this species