Ardea alba 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Pelecaniformes Ardeidae

Scientific Name: Ardea alba
Species Authority: Linnaeus, 1758
Regional Assessments:
Common Name(s):
English Great White Egret, Great White Heron, Great White Egret
French Grande aigrette
Ardea alba AOU checklist (1998 + supplements)
Ardea alba Christidis and Boles (1994)
Ardea alba SACC (2005)
Casmerodius albus (Linnaeus, 1758)
Egretta alba Turbott (1990)
Egretta alba Cramp and Simmons (1977-1994)
Egretta alba Dowsett and Forbes-Watson (1993)
Egretta alba Stotz et al. (1996)
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
Taxonomic Notes: Ardea alba (del Hoyo and Collar 2014) was previously placed in the genus Casmerodius as C. albus. Casmerodius albus (Sibley and Monroe 1990, 1993) was previously retained as a cross-regional species contra Christidis and Boles (2008) who moved C. albus into the genus Ardea and split it into two cross-regional species A. alba and A. modesta (note gender agreement of specific name for alba).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Butchart, S., 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 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.
Previously published Red List assessments:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Countries occurrence:
Afghanistan; Albania; Algeria; Angola (Angola); Anguilla; Antigua and Barbuda; Argentina; Armenia (Armenia); Aruba; Australia; Austria; Azerbaijan; Bahamas; Bahrain; Bangladesh; Barbados; Belarus; Belgium; Belize; Benin; Bhutan; Bolivia, Plurinational States of; Bonaire, Sint Eustatius and Saba; Bosnia and Herzegovina; Botswana; Brazil; Brunei Darussalam; Bulgaria; Burkina Faso; Burundi; Cambodia; Cameroon; Canada; Cayman Islands; Central African Republic; Chad; Chile; China; Christmas Island; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Costa Rica; Côte d'Ivoire; Croatia; Cuba; Curaçao; Cyprus; Czech Republic; Denmark; Dominica; Dominican Republic; Ecuador (Galápagos); Egypt; El Salvador; Eritrea; Ethiopia; Falkland Islands (Malvinas); France; French Guiana; Gabon; Gambia; Georgia; Germany; Ghana; Greece; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Hong Kong; Hungary; India; Indonesia; Iran, Islamic Republic of; Iraq; Israel; Italy; Jamaica; Japan; Jordan; Kazakhstan; Kenya; Korea, Democratic People's Republic of; Korea, Republic of; Kuwait; Kyrgyzstan; Lao People's Democratic Republic; Latvia; Lebanon; Lesotho; Liberia; Libya; Macao; Macedonia, the former Yugoslav Republic of; Madagascar; Malawi; Malaysia; Maldives; Mali; Martinique; Mauritania; Mayotte; Mexico; Micronesia, Federated States of ; Moldova; Mongolia; Montenegro; Montserrat; Morocco; Mozambique; Myanmar; Namibia; Nepal; Netherlands; New Zealand; Nicaragua; Niger; Nigeria; Northern Mariana Islands; Oman; Pakistan; Palau; Palestinian Territory, Occupied; Panama; Papua New Guinea; Paraguay; Peru; Philippines; Poland; Portugal; Puerto Rico; Qatar; Romania; Russian Federation; Rwanda; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Saudi Arabia; Senegal; Serbia (Serbia); Sierra Leone; Singapore; Sint Maarten (Dutch part); Slovakia; Slovenia; Solomon Islands; Somalia; South Africa; South Georgia and the South Sandwich Islands; South Sudan; Spain (Canary Is. - Vagrant); Sri Lanka; Sudan; Suriname; Swaziland; Switzerland; Syrian Arab Republic; Taiwan, Province of China; Tajikistan; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Trinidad and Tobago; Tunisia; Turkey; Turkmenistan; Turks and Caicos Islands; Uganda; Ukraine; United Arab Emirates; United States (Georgia); Uruguay; Uzbekistan; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Yemen; Zambia; Zimbabwe
British Indian Ocean Territory; Djibouti; Equatorial Guinea; Fiji; Finland; Ireland; Liechtenstein; Luxembourg; Malta; New Caledonia; Norway; Saint Helena, Ascension and Tristan da Cunha; Saint Pierre and Miquelon; Sao Tomé and Principe; Seychelles; Sweden; United Kingdom
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 57200000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme 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): 1500
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Estimate includes totals for 'Ardea modesta'.

Trend Justification:  The overall population trend is uncertain, as some populations are decreasing, while others are increasing, stable fluctuating or have unknown trends (Wetlands International 2006). This species has undergone a large and statistically significant increase over the last 40 years in North America (177% increase over 40 years, equating to a 29% increase per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the species's range in North America.
Current Population Trend: Unknown
Additional data:
Number of mature individuals: 590000-2200000 Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: Behaviour All populations of this species undergo post-breeding dispersive movements (del Hoyo et al. 1992). Populations breeding in the tropics are sedentary (del Hoyo et al. 1992) or partially migratory (in relation to rainfall) (Brown et al. 1982), whereas Palearctic and Nearctic populations are migratory (Flint et al. 1984, del Hoyo et al. 1992). The timing of the breeding season varies geographically (del Hoyo et al. 1992) although temperate breeders tend to nest in the spring and summer (e.g. April to July) and tropical breeders nest in the part of the rain cycle when food becomes maximally available (this may be during the rains or in the dry season) (Kushlan and Hancock 2005). The species typically breeds in colonies of tens, hundreds or even a thousand pairs (del Hoyo et al. 1992, Kushlan and Hancock 2005), sometimes with other species (e.g. 450 pairs in a mixed colony of over 3,000 nests in Australia) (del Hoyo et al. 1992). Some populations also show a tendency to breed solitarily or in small groups (del Hoyo et al. 1992). Outside of the breeding season the species may feed solitarily (del Hoyo et al. 1992) or in small loose groups (Marchant and Higgins 1990) (e.g. of 12-50 individuals) (Brown et al. 1982), although flocks of hundreds or more individuals may form where food is abundant (del Hoyo et al. 1992). The species is a diurnal feeder (del Hoyo et al. 1992) but is most active at dawn and dusk (although in coastal environments it feeding habits are determined by tidal stages) (Kushlan and Hancock 2005), and roosts at night in trees (Brown et al. 1982) alongside lakes or rivers or in mangroves, often with other species (Langrand 1990). Habitat The species inhabits all kinds of inland and coastal wetlands (del Hoyo et al. 1992) although it is mainly found along the coast in the winter (e.g. in the Palearctic Region) (Snow and Perrins 1998) or during droughts (e.g. in Australia) (Marchant and Higgins 1990). It frequents river margins, lakes shores, marshes, flood-plains (del Hoyo et al. 1992), oxbows, streams (Snow and Perrins 1998), damp meadows (Kushlan and Hancock 2005), rice-fields, drainage ditches (del Hoyo et al. 1992), aquaculture ponds, reservoirs (Marchant and Higgins 1990, Kushlan and Hancock 2005) and sewage works (Marchant and Higgins 1990, Hockey et al. 2005) inland, and the shallows of salt-lakes (Marchant and Higgins 1990), saltpans, mudflats, coastal swamps, mangroves (del Hoyo et al. 1992), saltmarshes, seagrass flats, offshore coral reefs, lagoons (Kushlan and Hancock 2005) and estuaries when in coastal locations (del Hoyo et al. 1992). Diet In aquatic habitats its diet consists of fish, amphibians, snakes, aquatic insects and crustaceans although in drier habitats terrestrial insects, lizards, small birds and mammals are more commonly taken (del Hoyo et al. 1992). Breeding site The nest is constructed from sticks (Kushlan and Hancock 2005) and vegetation (Brown et al. 1982) and is normally positioned over water at a height of 1-15 m (Kushlan and Hancock 2005) in reedbeds, bamboos (Kushlan and Hancock 2005), bushes, trees (del Hoyo et al. 1992) (e.g. willow Salix spp.), mangroves (Hancock and Kushlan 1984) and other plants near water or on islands in sites that are protected from ground predators (Kushlan and Hancock 2005). The species usually nests colonially in single- or mixed-species groups where nests may be less than 1 m apart or touching, although they are usually placed more spread out in reedbeds (Kushlan and Hancock 2005). Breeding pairs may also reuse nests from previous years (Kushlan and Hancock 2005). Management information Breeding site conservation should include colony protection, control of disturbance and vegetation management, and the conservation of feeding areas should include the management of hydrology, salt intrusion, contaminants and disturbance (Kushlan and Hancock 2005). An artificial island nesting site created in the Camargue, France succeeded in attracting nesting pairs to the area (Hafner 2000).
Systems: Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 9.1
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)

Threats [top]

Major Threat(s): The species is threatened by wetland habitat degradation and loss (Marchant and Higgins 1990, del Hoyo et al. 1992) for example through drainage, grazing, clearing, burning, increased salinity, groundwater extraction and invasion by exotic plants (Marchant and Higgins 1990). Breeding colonies in Madagascar may be declining due to egg and chick gathering from colonies by local peoples (Langrand 1990, Kushlan and Hancock 2005) and the species previously suffered from intense persecution for the plume trade (this is no longer a threat) (del Hoyo et al. 1992).

Citation: BirdLife International. 2015. Ardea alba. The IUCN Red List of Threatened Species 2015: e.T22697043A84959088. . Downloaded on 27 November 2015.
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