Gavia immer 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Gaviiformes Gaviidae

Scientific Name: Gavia immer (Brünnich, 1764)
Regional Assessments:
Common Name(s):
English Common Loon, Great Northern Diver, Great Northern Loon
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ashpole, J, Butchart, S., Calvert, R., Ekstrom, J., Malpas, L.
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 stable hence it is not believed 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:

Geographic Range [top]

Range Description:This species 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 (Eastern Asian Russia); Serbia; Turkey
Present - origin uncertain:
Austria; Bahamas; Bulgaria; Czech Republic; Germany; Italy; Romania; Slovakia; Slovenia; Sweden; Switzerland; Ukraine
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:27200000
Continuing decline in extent of occurrence (EOO):UnknownExtreme 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]

Population:Wetlands International (2016) estimated the population at 612,000-640,000 individuals. In Europe the breeding population is estimated at 700-1,300 pairs, which equates to 1,400-2,600 mature individuals (BirdLife International 2015).

Trend Justification:  The overall population trend is thought to be stable although some populations have unknown trends (Wetlands International 2016). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). In Europe and the EU27 the population is estimated and projected to be decreasing by 30-49% between 2000, when the declines are estimated to have begun and 2029 (three generations), and by at least 20% in 19.6 years (two generations) (BirdLife International 2015).
Current Population Trend:Stable
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll 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).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The species is listed under Appendix II of the Convention on Migratory Species and is listed under the African Eurasian Waterbird Agreement. It is listed in Article I under the EU Birds Directive. In Europe it occurs in 20 IBAs, including in Iceland, Norway (Svalbard and mainland Norway), Ireland, the United Kingdom and in Spain. It is a listed species in 83 Special Protection Areas in the EU Natura 2000 network. 

Conservation Actions Proposed
Protect Important Bird Areas across range states and identify and designate additional important sites. Identify sites and areas where high gillnet bycatch is occurring, and develop effective mitigation solutions. Manage coastal and inland developments surrounding important breeding areas. Develop rapid and trans-boundary response plans to coastal oil spills.

Citation: BirdLife International. 2016. Gavia immer. The IUCN Red List of Threatened Species 2016: e.T22697842A89564946. . Downloaded on 18 August 2018.
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