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Common Loon Gavia immer

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). 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.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
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.

Distribution and population
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).

Trend justification
The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2006). 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).

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).

Threats
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).

References
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.

Godfrey, W. E. 1979. The birds of Canada. National Museum of Natural Sciences, Ottawa.

Piper, W. H.; Meyer, M. W.; Klich, M.; Tischler, K. B.; Dolsen, A. 2002. Floating platforms increase reproductive success of common loons. Biological Conservation 104(2): 199-203.

Scheuhammer, A. M.; Money, S. L.; Kirk, D. A.; Donaldson, G. 2003. Lead fishing sinkers and jigs in Canada: review of their use patterns and toxic impacts on wildlife. Canadian Wildlife Service Occasional Papers 108: 1-45.

Sidor, I. F.; Pokras, M. A.; Major, A. R.; Poppenga, R. H.; Talyor, K. M.; Miconi, R. M. 2003. Mortality of common loons in New England, 1987-2000. Journal of Wildlife Diseases 39(2): 306-315.

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
Detailed species account from Birds in Europe: population estimates trends and conservation status (BirdLife International 2004)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Explore HBW Alive for further information on this species

View photos and videos and hear sounds of this species from the Internet Bird Collection

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

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Gavia immer. Downloaded from http://www.birdlife.org on 27/05/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/05/2016.

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.

Additional resources for this species

ARKive species - Common loon (Gavia immer)

Key facts
Current IUCN Red List category Least Concern
Family Gaviidae (Loons/Divers)
Species name author (Brünnich, 1764)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 2,970,000 km2
Country endemic? No
Links to further information
- Additional Information on this species
- 2015 European Red List assessment