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.

Family/Sub-family Ardeidae

Species name author Linnaeus, 1758

Taxonomic source(s) AERC TAC (2003), AOU checklist (1998 + supplements), Christidis and Boles (2008), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), SACC (2005 + updates), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

790,000 - 3,700,000

unset

99,700,000 km²

No

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

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 February². 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 200-250¹. 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)². 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 nests². The species is typically a solitary feeder but at abundant temporary food sources, or where available feeding areas are restricted, large congregations may occur^{2, 6}. It feeds at any time day or night, but is most active at dawn or dusk, typically roosting communally or solitarily¹ during the middle of the day and at night² in trees and on cliffs, low rocks, islets or along shores¹. 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 habitat². It occurs from sea-level up to 500 or even 1,000 m, occasionally breeding much higher⁶ (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 nesting². 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^{1, 2, 6}, river oxbows, reservoirs, ditches, canals, sewage farms, inland deltas, and on islets and emerging rocks⁶. On the coast the species also frequents deltas, salt-marshes, mangroves^{1, 2}, estuaries, tidal mudflats, muddy and sandy shores, and sand-spits⁶. 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^{1, 2, 6} and plant matter (although this may be incidental, or only to aid in pellet formation)^{1, 2, 6}. Breeding site The nest is a stick platform that is often re-used over successive years², 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 debris⁶. The species commonly nests in colonies, and nesting sites are typically situated 2-38 km (convenient flying distance) from preferred feeding areas².

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 farmers². Although killing at aquaculture farms has not reduced the global population so far (possibly because it is young birds that are mostly killed)², 800 herons are estimated to have died per year at Scottish fish-farms between 1984 and 1987^{2, 5} by being shot, drowned or poisoned by fish farmers⁵. 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)². 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)^{3, 4}, hunting, and predation at nesting colonies^{2, 4}. Timber harvesting is a threat throughout much of the species range by removing trees used by nesting colonies and/or disturbing nearby colonies². The species is also susceptible to avian influenza⁷ and avian botulism⁹, so may be threatened by future outbreaks of these diseases. Utilisation The species is hunted and traded at traditional medicine markets in Nigeria⁸.

References del Hoyo et al. (1992). 1. Brown et al. (1982). 2. Kushlan and Hancock (2005). 3. Hafner and Kushlan (2002). 4. Kushlan and Hafner (2000). 5. Carss (1994). 6. Snow and Perrins (1998). 7. Melville and Shortridge (2006). 8. Nikolaus (2001). 9. van Heerden (1974).

Further web sources of information

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

Text account compilers Stuart Butchart (BirdLife International), Jonathan Ekstrom (BirdLife International), Lucy Malpas (BirdLife International)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International)

Recommended citation BirdLife International (2010) Species factsheet: Ardea cinerea. Downloaded from http://www.birdlife.org on 30/7/2010

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.

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