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LC
Grey Heron Ardea cinerea

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 is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds 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#.
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
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.
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Population justification
The global population is estimated to number c.790,000-3,700,000 individuals (Wetlands International 2006), while national population estimates include: c.100,000-1 million breeding pairs and >c.10,000 individuals on migration in China; c.100-10,000 breeding pairs and c.1,000-10,000 wintering individuals in Korea; c.100,000-1 million breeding pairs and >c.10,000 wintering individuals in Japan and c.100,000-1 million breeding pairs and >c.10,000 individuals on migration in Russia (Brazil 2009).

Trend justification
The overall population trend is uncertain, as some populations are decreasing, while others are stable, increasing or have unknown trends (Wetlands International 2006). 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 Most Palearctic populations of this species are fully migratory, dispersing widely in September-October after the breeding season and returning to breeding grounds in February (Kushlan and Hancock 2005). Further south, populations tend to be sedentary or only partially migratory. Most migratory movements occur nocturnally, with birds moving in small parties or larger flocks of 200-250 (Brown et al. 1982). The species breeds January-May in the Palearctic Region, and in spring and summer in temperate areas, but mainly during the rains in Africa and the tropics(although here it may also breed in any month of the year) (Kushlan and Hancock 2005). It breeds in mixed colonies of hundreds or thousands of pairs (the largest colony in Europe is 800-1,300 pairs), although it may also nest solitarily or in small groups of 2-10 nests (Kushlan and Hancock 2005). The species is typically a solitary feeder but at abundant temporary food sources, or where available feeding areas are restricted, large congregations may occur (Snow and Perrins 1998, Kushlan and Hancock 2005). It feeds at any time day or night, but is most active at dawn or dusk, typically roosting communally or solitarily (Brown et al. 1982) during the middle of the day and at night (Kushlan and Hancock 2005) in trees and on cliffs, low rocks, islets or along shores (Brown et al. 1982). Habitat This species is a generalist in its habitat use, although shallow water, relatively large prey, and four or five months of ice-free breeding season are among the essential characteristics of its habitat (Kushlan and Hancock 2005). It occurs from sea-level up to 500 or even 1,000 m, occasionally breeding much higher (Snow and Perrins 1998) (2,000 m in Armenia, 3,500-4,000 m in Ladakh, north-west India), inhabits any kind of shallow water, either fresh, brackish or saline, both standing or flowing, and shows a preference for areas with trees as it is commonly an arboreal rooster and nester. Some degree of isolation and protection are also typical of places chosen for roosting and nesting (Kushlan and Hancock 2005). The species is found inland on broad rivers, narrow streams, lake shores, ornamental ponds, fish-ponds, marshes, flood-plains, reeds swamps, rice-fields and other irrigated areas (Brown et al. 1982, Snow and Perrins 1998, Kushlan and Hancock 2005), river oxbows, reservoirs, ditches, canals, sewage farms, inland deltas, and on islets and emerging rocks (Snow and Perrins 1998). On the coast the species also frequents deltas, salt-marshes, mangroves (Brown et al. 1982, Kushlan and Hancock 2005), estuaries, tidal mudflats, muddy and sandy shores, and sand-spits (Snow and Perrins 1998). Diet Its diet consists predominantly of fish and eels 10-25 cm long, as well as amphibians, crabs, molluscs, crustaceans, aquatic insects, snakes, small rodents, small birds (Brown et al. 1982, Snow and Perrins 1998, Kushlan and Hancock 2005) and plant matter (although this may be incidental,or only to aid in pellet formation) (Brown et al. 1982, Snow and Perrins 1998, Kushlan and Hancock 2005). Breeding site The nest is a stick platform that is often re-used over successive years (Kushlan and Hancock 2005), usually positioned high in a tall tree up to 50 m, but also on the ground or on cliff edges, in reedbeds or in bushes. In reed-beds nests may be built of reeds, and ground nests may be reduced to a slight scrape, ringed with small stones and debris (Snow and Perrins 1998). The species commonly nests in colonies, and nesting sites are typically situated 2-38 km (convenient flying distance) from preferred feeding areas (Kushlan and Hancock 2005).

Threats
In Europe the species was heavily persecuted in the nineteenth century due to its consumption of fish, which resulted in competition with fishermen and fish farmers (Kushlan and Hancock 2005). Although killing at aquaculture farms has not reduced the global population so far (possibly because it is young birds that are mostly killed) (Kushlan and Hancock 2005), 800 herons are estimated to have died per year at Scottish fish-farms between 1984 and 1987 (Carss 1994, Kushlan and Hancock 2005) by being shot, drowned or poisoned by fish farmers (Carss 1994). Renewed hunting poses a threat to Bavarian populations by decreasing numbers to levels that inhibit recovery following severe winters (severe winters increase mortality rates for juveniles) (Kushlan and Hancock 2005). The species is vulnerable in Madagascar owing to its restricted range, exceedingly high levels of habitat alteration (from siltation and the need for agricultural land for rice and grazing) (Kushlan and Hafner 2000, Hafner and Kushlan 2002), hunting, and predation at nesting colonies (Kushlan and Hafner 2000, Kushlan and Hancock 2005). Timber harvesting is a threat throughout much of the species range by removing trees used by nesting colonies and/or disturbing nearby colonies (Kushlan and Hancock 2005). The species is also susceptible to avian influenza (Melville and Shortridge 2006)and avian botulism (van Heerden 1974), so may be threatened by future outbreaks of these diseases. Utilisation The species is hunted and traded at traditional medicine markets in Nigeria (Nikolaus 2001).

References
Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

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

Carss, D. N. 1994. Killing of piscivorous birds at Scottish fin fish farms, 1984-1987. Biological Conservation 68: 181-188.

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.

Hafner, H.; Kushlan, J. A. 2002. Action plan for conservation of the Herons of the world. Heron Specialist Group, Gland, Cambridge and Arles.

Kushlan, J. A.; Hancock, J. A. 2005. The herons. Oxford University Press, Oxford, U.K.

Melville, D. S.; Shortridge, K. F. 2006. Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.

Nikolaus, G. 2001. Bird exploitation for traditional medicine in Nigeria. Malimbus 23: 45-55.

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

van Heerden, J. 1974. Botulism in the Orange Free State goldfields. Ostrich 45(3): 182-184.

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

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Species factsheet from HeronConservation - The IUCN-SSC Heron Specialist Group

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

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

Recommended citation
BirdLife International (2014) Species factsheet: Ardea cinerea. Downloaded from http://www.birdlife.org on 27/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/11/2014.

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 - Grey heron (Ardea cinerea) 0

Key facts
Current IUCN Red List category Least Concern
Family Ardeidae (Herons)
Species name author Linnaeus, 1758
Population size mature individuals
Population trend Unknown
Distribution size (breeding/resident) 62,100,000 km2
Country endemic? No
Links to further information
- Additional Information on this species
- Projected distributions under climate change