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LC
Western Marsh-harrier Circus aeruginosus

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 10 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 10 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.

Population justification
In Europe, the breeding population is estimated to number 93,000-140,000 breeding pairs, equating to 279,000-420,000 individuals (BirdLife International 2004). Europe forms 25-49% of the global range, so a very preliminary estimate of the global population size is 0.5-2 million individuals, although further validation of this estimate is needed.

Trend justification
In Europe, trends since 1980 show that populations have undergone a moderate increase (p<0.01), based on provisional data for 21 countries from the Pan-European Common Bird Monitoring Scheme (EBCC/RSPB/BirdLife/Statistics Netherlands; P. Vorisek in litt. 2008).

Ecology

Behaviour It is mainly migratory, with populations in Western Europe, North Africa and at the south of its range in Asia being generally resident (del Hoyo et al. 1994, Ferguson-Lees and Christie 2001). Migrant birds leave their breeding grounds in September and October, wintering from France south as far as sub-Saharan Africa, and east as far as the Middle East (del Hoyo et al. 1994). They begin their return journey in February and March, arriving in March and April (del Hoyo et al. 1994, Snow and Perrins 1998, Ferguson-Lees and Christie 2001). Migration is generally on a broad front, although there is some concentration at a few sites (Brown et al. 1982). Hundreds of birds occasionally gather at roosting sites, sometimes with other harriers such as C. pygargus, but otherwise they are usually solitary, associating only temporarily at especially rich feeding sites (del Hoyo et al. 1994, Snow and Perrins 1998, Ferguson-Lees and Christie 2001). They have a slightly greater tendency to be gregarious while on migration but the above still generally applies. Birds fly c.10-30 m above the ground (Brown et al. 1982). Habitat The species inhabits extensive areas of dense marsh vegetation, in fresh or brackish water, generally in lowlands but up to 2,000 m in Asia and 3,000 m on its wintering grounds in Cameroon (del Hoyo et al. 1994). Diet It is a generalist predator taking a variety of prey types, with small birds generally preferred but mammals such as voles, rabbits and rats being more important in parts of its range (del Hoyo et al. 1994). Breeding site The nest is a pile of reeds built in dense marsh vegetation (del Hoyo et al. 1994). Management information The species requires extensive wetland in its breeding range (del Hoyo et al. 1994).

Threats

Major threats include wetland desiccation and drainage; persecution by shooting; pollution, especially from excessive pesticide use in and around wetlands (although widespread bans have reduced this threat somewhat), and poisoning by heavy metals, notably the consumption of lead-shot through feeding on contaminated waterbirds (del Hoyo et al. 1994, Ferguson-Lees and Christie 2001). The historical threat of hunting in southern Europe has mostly subsided, but illegal shooting is still rife locally, notably on Malta (Ferguson-Lees and Christie 2001). The species is also highly vulnerable to the effects of potential wind energy development (Strix 2012).

References
BirdLife International. 2004. Birds in Europe: population estimates, trends and conservation status. BirdLife International, Cambridge, U.K.

Brown, L. H.; Urban, E. K.; Newman, K. 1982. The birds of Africa vol I. Academic Press, London.

del Hoyo, J.; Elliott, A.; Sargatal, J. 1994. Handbook of the Birds of the World, vol. 2: New World Vultures to Guineafowl. Lynx Edicions, Barcelona, Spain.

Ferguson-Lees, J.; Christie, D. A. 2001. Raptors of the world. Christopher Helm, London.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Strix. 2012. Developing and testing the methodology for assessing and mapping the sensitivity of migratory birds to wind energy development. BirdLife International, Cambridge.

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

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Text account compilers
Butchart, S., Ekstrom, J., Harding, M., Khwaja, N.

Contributors
Vorisek, P.

Recommended citation
BirdLife International (2014) Species factsheet: Circus aeruginosus. Downloaded from http://www.birdlife.org on 25/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/07/2014.

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 - Marsh harrier (Circus aeruginosus) 0

Key facts
Current IUCN Red List category Least Concern
Family Accipitridae (Hawks, Eagles)
Species name author (Linnaeus, 1758)
Population size mature individuals
Population trend Increasing
Distribution size (breeding/resident) 13,500,000 km2
Country endemic? No
Links to further information
- Additional Information on this species