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Cygnus olor

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES ANSERIFORMES ANATIDAE

Scientific Name: Cygnus olor
Species Authority: (Gmelin, 1789)
Common Name(s):
English Mute Swan

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Malpas, L., Ekstrom, J., Butchart, S.
Justification:
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). 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). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Geographic Range [top]

Countries:
Native:
Afghanistan; Albania; Armenia (Armenia); Austria; Azerbaijan; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; China; Croatia; Cyprus; Czech Republic; Denmark; Estonia; Finland; France; Germany; Greece; Hungary; India; Iran, Islamic Republic of; Iraq; Ireland; Israel; Italy; Japan; Kazakhstan; Korea, Democratic People's Republic of; Korea, Republic of; Kyrgyzstan; Latvia; Liechtenstein; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Moldova; Mongolia; Montenegro; Netherlands; Norway; Pakistan; Poland; Romania; Russian Federation; Serbia (Serbia); Slovakia; Slovenia; Spain (Canary Is. - Vagrant); Sweden; Switzerland; Taiwan, Province of China; Turkey; Turkmenistan; Ukraine; United Kingdom; Uzbekistan
Introduced:
Australia; Canada; Faroe Islands; Iceland; New Zealand; Singapore; South Africa; United States
Vagrant:
Bahrain; Bermuda; Egypt; Jordan; Lebanon; Libya; Malta; Morocco; Oman; Palestinian Territory, Occupied; Portugal; Syrian Arab Republic; Tajikistan; United Arab Emirates
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population is estimated to number c.600,000-610,000 individuals (Wetlands International 2006), while national population estimates include: <c.100 breeding pairs and <c.1,000 wintering individuals in China; <c.50 individuals on migration and <c.50 wintering individuals in Korea and c.100-10,000 introduced breeding pairs in Japan (Brazil 2009).
Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology: Behaviour Truly wild populations of this species are migratory (particularly where displaced by cold weather) (del Hoyo et al. 1992, Snow and Perrins 1998) although European and feral populations are essentially sedentary (Johnsgard 1978, del Hoyo et al. 1992, Scott and Rose 1996, Snow and Perrins 1998) or only locally migratory or nomadic (Scott and Rose 1996, Snow and Perrins 1998). The species breeds during the local spring (del Hoyo et al. 1992, Kear 2005a)as isolated pairs in well-defended territories (del Hoyo et al. 1992). After breeding the adults may gather in large concentrations of thousands or more (Johnsgard 1978, Madge and Burn 1988) on selected waters (Madge and Burn 1988) (non-breeders in northern Europe migrating to such gatherings (Snow and Perrins 1998)) between July and August (Scott and Rose 1996) to undergo a flightless moulting period lasting for 6-8 weeks (Kear 2005a). Although not noticeably sociable in many areas during the winter (Johnsgard 1978) the species may flock in groups of several thousands on favoured waters (Johnsgard 1978, Madge and Burn 1988, Scott and Rose 1996). Habitat The species inhabits a variety of lowland freshwater wetlands (del Hoyo et al. 1992) such as shallow lakes (Kear 2005a), ponds (Madge and Burn 1988), lagoons, marshes (del Hoyo et al. 1992), reedbeds (del Hoyo et al. 1992, Snow and Perrins 1998) and slow-flowing rivers (Kear 2005a) (showing a preference for clean, weed-filled streams over larger, polluted rivers) (Johnsgard 1978). It is also common on artificial waterbodies such as reservoirs, gravel-pits, ornamental lakes (del Hoyo et al. 1992), ditches (Snow and Perrins 1998) and canals (Scott and Rose 1996), and will graze on grassland and agricultural land (e.g. arable cereal fields) (Kear 2005a). Moulting congregations of adults and non-breeders (Snow and Perrins 1998) may also utilise brackish or saline habitats (Johnsgard 1978) including brackish marshes (Kear 2005a), estuaries and sheltered coastal sites (del Hoyo et al. 1992) (e.g. brackish lagoons (Kear 2005a) and bays (Madge and Burn 1988)). Diet Its diet consists predominantly of leaves and the vegetative parts of aquatic plants (Johnsgard 1978, del Hoyo et al. 1992) and grasses (del Hoyo et al. 1992) as well as algae (Johnsgard 1978) and grain (del Hoyo et al. 1992), occasionally also taking small amphibians (Johnsgard 1978, del Hoyo et al. 1992) (frogs, toads and tadpoles) (Snow and Perrins 1998) and aquatic invertebrates (e.g. molluscs, insects and worms) (Johnsgard 1978, del Hoyo et al. 1992). Breeding site The nest is a large mound of aquatic vegetation (del Hoyo et al. 1992, Kear 2005a) placed close to or floating on shallow water (del Hoyo et al. 1992, Kear 2005a) or amongst reeds (del Hoyo et al. 1992). Breeding pairs often re-use nesting sites from previous years if the it was successful (Johnsgard 1978). Management information The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK resulted in an increase in the growth of submerged aquatic macrophytes and in turn led to an increase in the winter use of the habitat by the species (Giles 1994). The removed fish (dead or alive) were sold to generate funds (Giles 1994). A control of the breeding output of the species (brood reduction) carried out in the Wylye Valley, UK to try to alleviate the species's negative impacts on fisheries (e.g. by overgrazing submergent riverine vegetation) was found to be ineffective as it had an insignificant impact on local population sizes (possibly due to immigration from surrounding areas) (Watola et al. 2003).
Systems: Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s): The species suffers heavy losses from lead poisoning due to ingested lead fishing weights (del Hoyo et al. 1992, Kelly and Kelly 2004), lead shot (Spray and Milne 1988) and lead contaminated sediments from mining and smelting activities (Day et al. 2003). Heavy losses have also been recorded from local incidences of copper poisoning (Kobayashi et al. 1992). The ingestion of or entanglement in fishing lines and/or hooks can also cause severe injury or mortality (Kelly and Kelly 2004) as can collisions with overhead lines (del Hoyo et al. 1992). The species may be threatened by future oil spills (which can cause death by oil saturation) (Berglund et al. 1963). The species is also susceptible to avian influenza (Melville and Shortridge 2006)(e.g. strain H5N1) (Nagy et al. 2007) so may be threatened by future outbreaks of the virus.

Citation: BirdLife International 2012. Cygnus olor. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 July 2014.
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