Gavia immer 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Gaviiformes Gaviidae

Scientific Name: Gavia immer
Species Authority: (Brünnich, 1764)
Regional Assessments:
Common Name(s):
English Common Loon, Great Northern Diver, Great Northern Loon
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.

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., Butchart, S., Ekstrom, J., Calvert, R.
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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to 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.
Previously published Red List assessments:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: The Common Loon breeds in much of Canada and Alaska, parts of northern United States, southern parts of Greenland (to Denmark) and in Iceland. It winters on sea coasts or on larger lakes over a much wider area including the Antlantic coast of Europe from Finland to Portugal and the western Mediterranean, the Atlantic coast of North America down to northern Mexico, and the Pacific coast of North America from northern Mexico to the tip of Alaska (USA) (del Hoyo et al 1992).
Countries occurrence:
Belgium; Canada; Cuba; Denmark; Faroe Islands; France; Greenland; Iceland; Ireland; Mexico; Netherlands; Norway; Portugal; Saint Pierre and Miquelon; Spain (Canary Is. - Vagrant); Svalbard and Jan Mayen; United Kingdom; United States
Albania; Algeria; Bermuda; Croatia; Estonia; Finland; Gibraltar; Greece; Hungary; Lithuania; Luxembourg; Montenegro; Morocco; Poland; Russian Federation; Serbia (Serbia); Turkey
Present - origin uncertain:
Austria; Bahamas; Bulgaria; Czech Republic; Germany; Italy; Romania; Slovakia; Slovenia; Sweden; Switzerland; Ukraine
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 2970000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 500
Range Map: Click here to open the map viewer and explore range.

Population [top]

Current Population Trend: Decreasing
Additional data:
Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: Behaviour This species is strongly migratory, with inland breeding populations moving south or to the coast after breeding (del Hoyo et al 1992). The species breeds from May onwards in isolated solitary pairs, nesting later further to the north depending on the timing of the thaw (del Hoyo et al 1992). Adults become flightless for a short time in late-winter when they moult their flight feathers (Godfrey 1979). During the winter the species occurs singly, in pairs or in small loose flocks in marine habitats (Godfrey 1979, Snow and Perrins 1998), occasionally also forming large congregations of c.300 (Godfrey 1979, del Hoyo et al 1992). Habitat Breeding The species breeds on large, deep freshwater lakes in coniferous forest or on open tundra (del Hoyo et al 1992), requiring clear water with visibilities of at least 3-4 m and small islands (less than 2.5 ha) for nesting (Rimmer 1992). Non-breeding It winters along the coast on exposed rocky shores, sheltered bays (del Hoyo et al 1992), channels and sheltered inlets (Snow and Perrins 1998) showing a preference for shallow inshore waters (Rimmer 1992). It may also be found inland (del Hoyo et al 1992) on lakes and reservoirs during this season (Snow and Perrins 1998), although this is largely influenced by the weather (Rimmer 1992). Diet Its diet consists predominantly of fish as well as crustaceans, molluscs, aquatic insects, annelid worms, frogs, other amphibiansand plant matter (e.g. Potamogeton spp., willow Salix spp. shoots, roots, seeds, moss and algae) (del Hoyo et al 1992). Breeding site The nest is a mound of plant matter screened by vegetation (Snow and Perrins 1998) and placed near the water's edge (del Hoyo et al 1992) on islands, islets or promontories (Snow and Perrins 1998). Management information There is evidence that introducing floating nesting platforms on lakes is successful in increasing the reproductive success of the species (Piper et al. 2002)7, and that nest losses caused by flooding can be reduced by controlling water levels during the nesting period (Rimmer 1992). Mortality from entanglement and drowning in fishing nets could also be reduced by using fish traps with openings at the top to allow birds to escape, or by checking traps more regularly for captured birds (Rimmer 1992).
Systems: Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 9.8
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)

Threats [top]

Major Threat(s): When breeding the species is threatened by fluctuating water levels (del Hoyo et al 1992) (e.g. due to the building of dams) (Rimmer 1992), acidification of breeding lakes (del Hoyo et al 1992, Piper et al. 2002)7, heavy metal pollution (del Hoyo et al 1992, Rimmer 1992) (e.g. methylmercury contamination) (Piper et al. 2002) and lead poisoning from ingested lead fishing weights (Scheuhammer et al. 2003, Sidor et al. 2003). It is also highly sensitive to human disturbance (del Hoyo et al 1992) such as shoreline development and human recreation (Piper et al. 2002)7, and may desert lakes after increases in human presence and activities (del Hoyo et al 1992). During the winter the species is highly vulnerable to coastal oil spills, especially in areas where large congregations form (del Hoyo et al 1992), and entanglement in monofilament fishing lines (used for sport fishing) and commercial fishing nets causes significant mortality at sea and on larger lakes (del Hoyo et al 1992, Rimmer 1992). The species is also susceptible to avian botulism so may be threatened by future outbreaks of the disease (del Hoyo et al 1992, Rimmer 1992).

Citation: BirdLife International. 2012. Gavia immer. The IUCN Red List of Threatened Species 2012: e.T22697842A40155246. . Downloaded on 29 May 2016.
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