Mergellus albellus -- (Linnaeus, 1758) ANIMALIA -- CHORDATA -- AVES -- -- Common names: Smew; European Red List Assessment European Red List Status LC -- Least Concern, (IUCN version 3.1) Assessment Information Year published: 2015 Date assessed: 2015-03-31 Assessor(s): BirdLife International Reviewer(s): Symes, A. Compiler(s): Ashpole, J., Burfield, I., Ieronymidou, C., Pople, R., Wheatley, H. & Wright, L. Assessment Rationale European regional assessment: Least Concern (LC) EU27 regional assessment: Least Concern (LC)

In this species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence 10% in ten years or three generations, or with a specified population structure). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern in Europe.

Within the EU27 this species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence 10% in ten years or three generations, or with a specified population structure). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern in the EU27. Occurrence Countries/Territories of Occurrence Native: Albania; Austria; Azerbaijan; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Czech Republic; Denmark; Estonia; Finland; France; Germany; Greece; Hungary; Ireland, Rep. of; Italy; Latvia; Liechtenstein; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Moldova; Montenegro; Netherlands; Norway; Poland; Romania; Russian Federation; Serbia; Slovakia; Slovenia; Spain; Sweden; Switzerland; Turkey; Ukraine; United Kingdom Vagrant: Cyprus; Iceland; Malta; Portugal; Gibraltar (to UK) Population The European population is estimated at 9,200-17,600 pairs, which equates to 18,300-35,200 mature individuals. The population in the EU27 is estimated at 3,100-7,500 pairs, which equates to 6,200-15,000 mature individuals. For details of national estimates, see Supplementary PDF. Trend In Europe the population size is estimated to be increasing. In the EU27 the population size is estimated to be stable. For details of national estimates, see Supplementary PDF. Habitats and Ecology It breeds on freshwater oligotrophic lakes, pools, oxbow lakes, backwaters of large slow-flowing rivers, muskegs (bogs) (Kear 2005) and flooded riverside woods (Johnsgard 1978, Snow and Perrins 1998) in the coniferous and mixed deciduous/evergreen forest zones (Snow and Perrins 1998, Carboneras and Kirwan 2014). It shows a preference for shallow water, and requires mature broadleaved trees with holes in which to nest (Johnsgard 1978). The species overwinters on large freshwater lakes, brackish coastal lagoons, estuaries (Carboneras and Kirwan 2014), reservoirs (Johnsgard 1978), ice-free rivers (Kear 2005) and sheltered coastal bays (Madge and Burn 1988) (although rarely on the open sea) (Carboneras and Kirwan 2014), often resting and feeding on small bodies of water or small streams when on passage (Kear 2005). It arrives on the breeding grounds from April (Kear 2005) or early-May and breeds from mid-May onwards (Madge and Burn 1988). The species nests in tree hollows (Carboneras and Kirwan 2014) up to 10 m or more above the ground (Kear 2005) in mature broadleaved trees (Johnsgard 1978). It may also nest in artificial nest boxes. Typically it lays seven to nine eggs (Carboneras and Kirwan 2014). During the breeding season its diet consists predominantly of benthic aquatic invertebrates such as adult and larval, crustaceans, molluscs and polychaete worms, as well as fish (Kear 2005), amphibians and plant matter. During the winter and in early spring however the species mainly feeds on fish. This species is highly migratory (Carboneras and Kirwan 2014). Habitats & Altitude Habitat (level 1 - level 2) Importance Occurrence Artificial/Aquatic - Water Storage Areas (over ha) suitable non-breeding Forest - Boreal major breeding Marine Coastal/Supratidal - Coastal Brackish/Saline Lagoons/Marine Lakes suitable non-breeding Marine Neritic - Estuaries suitable non-breeding Wetlands (inland) - Bogs, Marshes, Swamps, Fens, Peatlands suitable breeding Wetlands (inland) - Permanent Freshwater Lakes (over ha) major breeding Wetlands (inland) - Permanent Freshwater Lakes (over ha) major non-breeding Wetlands (inland) - Permanent Freshwater Marshes/Pools (under ha) suitable breeding Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls) suitable breeding Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls) suitable non-breeding Altitude Occasional altitudinal limits Threats Where it occurs in large numbers on coastal waters the species is particularly vulnerable to oil pollution (Carboneras and Kirwan 2014). Populations declined in Europe throughout the 19th and 20th centuries due to habitat degradation and loss (e.g. the loss of mature trees in river valleys as a result of logging, conversion to agriculture and river canalisation). The species has also suffered local declines as a result of predation by American mink (Neovison vison) (Kear 2005) and is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006). The species is susceptible to a certain amount of hunting pressure when on passage and during the winter (Carboneras and Kirwan 2014). Climate change is also affecting the range of this species (Pavón-Jordán et al. 2015). Threats & Impacts Threat (level 1) Threat (level 2) Impact and Stresses Agriculture & Agro-industry Timing Scope Severity Impact aquaculture farming Past, Likely to Majority (50-90%) Slow, Significant Past Impact Return Declines Stresses Ecosystem conversion; Ecosystem degradation Biological resource Hunting & trapping Timing Scope Severity Impact use terrestrial Ongoing Minority (<50%) Negligible declines Low Impact (intentional use - species is the target) Stresses Species mortality Biological resource Logging & wood Timing Scope Severity Impact use harvesting Past, Likely to Majority (50-90%) Slow, Significant Past Impact (unintentional Return Declines effects: (large scale) [harvest]) Stresses Ecosystem conversion; Ecosystem degradation Climate change & Habitat shifting & Timing Scope Severity Impact severe weather alteration Future Whole (>90%) Unknown Unknown Stresses Ecosystem degradation; Indirect ecosystem effects Threats & Impacts Threat (level 1) Threat (level 2) Impact and Stresses Invasive and other American Mink Timing Scope Severity Impact problematic (Neovison vison) Ongoing Minority (<50%) Slow, Significant Low Impact species, genes & Declines diseases Stresses Species mortality Invasive and other Avian Influenza Timing Scope Severity Impact problematic Virus (H subtype) Past, Likely to Majority (50-90%) Rapid Declines Past Impact species, genes & Return diseases Stresses Species mortality Natural system Other ecosystem Timing Scope Severity Impact modifications modifications Past, Unlikely to Minority (<50%) Slow, Significant Past Impact Return Declines Stresses Ecosystem conversion; Ecosystem degradation Pollution Oil spills Timing Scope Severity Impact Past, Unlikely to Majority (50-90%) Causing/Could Past Impact Return cause fluctuations Stresses Ecosystem degradation; Species mortality; Reduced reproductive success Conservation Conservation Actions Underway CMS Appendix II. Bern Convention Appendix II. EU Directive Annex I. The total population of this species wintering in north-east Europe has increased from 6% to a third in two decades. SPAs have proven effective in accommodating this range shift, with population growth in this region doubling inside EU Birds Directive's SPAs compared to those outside over the last 25 years (Pavón-Jordán et al. 2015).

Conservation Actions Proposed Gaps in the current network of protected areas need to be filled and national and international assessments of the EU Natura 2000 network should be made regularly (Pavón-Jordán et al. 2015). Strict legislation on oil transportation needs to be implemented and enforced to minimise the risk of spills. Investigation into the impacts of American Mink should be undertaken and suitable eradication methods trialled. In areas where the species is hunted, research and legislation is needed to ensure that it is sustainable. Bibliography Carboneras, C. and Kirwan, G.M. 2014. Smew (Mergellus albellus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds.) 2014. Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/52927 on 3 March 2015). Johnsgard, P.A. 1978. , 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 ). Oxford University Press, Oxford, U.K. Madge, S. and Burn, H. 1988. Wildfowl. Christopher Helm, London. Melville, D.S. and 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. and Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK. Pavón-Jordán, D., Fox, A.D., Clausen, P., Dagys, M., Deceuninck, B., Devos, K., Hearn, R.D., Holt, C.A., Hornman, M., Keller, V., Langendoen, T., Ławicki, Ł., Lorentsen, S.H., Luigujõe, L., Meissner, W., Musil, P., Nilsson, L., Paquet, J.-Y., Stipniece, A., Stroud, D.A., Wahl, J., Zenatello, M. and Lehikoinen, A. (2015), Climate-driven changes in winter abundance of a migratory waterbird in relation to EU protected areas. Diversity and Distributions, 21(5): 571-582. Snow, D.W. and Perrins, C.M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford. Map (see overleaf)