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 ten years or three generations). The population size is extremely 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#.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Synonym(s)
Ardea ibis Christidis and Boles (1994), Ardea ibis Christidis and Boles (2008), Ardeola ibis Stotz et al. (1996)
The population is estimated to number 3,800,000-7,600,000 individuals.
Trend justification
The overall population trend is increasing, although some populations may be stable or decreasing and others have unknown trends (Wetlands International 2006). This species has undergone a small or statistically insignificant decrease over the last 40 years in North America (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.
Ecology
Behaviour Most populations of this species are partially migratory, making long-distance dispersive movements related to food resources in connection with seasonal rainfall (del Hoyo et al. 1992). Other populations (e.g. in north-east Asia and North America) are fully migratory (del Hoyo et al. 1992, Snow and Perrins 1998). The species breeds throughout the year in the tropics with different regional peaks (del Hoyo et al. 1992) depending on food availability (Kushlan and Hancock 2005). It breeds colonially, often with other species, in groups that number from a few dozen to several thousand pairs, even up to 10,000 pairs in Africa (del Hoyo et al. 1992). The nesting effort of the species is related to rainfall patterns, leading to an annual variation in productivity (Kushlan and Hancock 2005). Outside of the breeding season the species remains gregarious (Brown et al. 1982, del Hoyo et al. 1992), feeding in loose flocks of 10-20 individuals (Brown et al. 1982) and often gathering in flocks of hundreds or even thousands of individuals where food is abundant (del Hoyo et al. 1992). Nocturnal roosting sites in Africa commonly hold a few hundred to 2,000 individuals (Brown et al. 1982). The species is a diurnal feeder (del Hoyo et al. 1992) and commonly associates with native grazing mammals or domesticated livestock (Kushlan and Hancock 2005) and may follow farm machinery to capture disturbed prey (del Hoyo et al. 1992). Habitat The species inhabits open grassy areas such as meadows (del Hoyo et al. 1992), livestock pastures (Kushlan and Hancock 2005), semi-arid steppe (del Hoyo et al. 1992) and open savanna grassland subject to seasonal inundation (Kushlan and Hancock 2005), dry arable fields (del Hoyo et al. 1992), artificial grassland sites (e.g. lawns, parks, road margins and sports fields) (Kushlan and Hancock 2005), flood-plains (Hancock and Kushlan 1984), freshwater swamps, rice-fields, wet pastures (del Hoyo et al. 1992), shallow marshes (Kushlan and Hancock 2005), mangroves (Hancock and Kushlan 1984) and irrigated grasslands (with ponds, small impoundments, wells, canals, small rivers and streams) (Kushlan and Hancock 2005). It rarely occupies marine habitats or forested areas (del Hoyo et al. 1992) although in Australia it may enter woodlands and forests, and it shows a preference for freshwater (Marchant and Higgins 1990) although it may also use brackish or saline habitats (Kushlan and Hancock 2005). It occurs from sea-level up to c.1,500 m (Kushlan and Hancock 2005) or locally up to c.4,000 m (Peru) (del Hoyo et al. 1992). Diet Its diet consists primarily of insects such as locusts, grasshoppers (del Hoyo et al. 1992), beetles, adult and larval Lepidoptera, Hemiptera, dragonflies (Hancock and Kushlan 1984) and centipedes but worms (Brown et al. 1982), spiders (Hancock and Kushlan 1984), crustaceans, frogs, tadpoles, molluscs, fish, lizards, small birds, rodents and vegetable matter (e.g. palm-nut pulp) may also be taken (del Hoyo et al. 1992). Breeding site The nest is constructed of twigs and vegetation (Kushlan and Hancock 2005) and is positioned up to 20 m high in reedbeds (del Hoyo et al. 1992, Kushlan and Hancock 2005), marshes, mangroves, dense thickets (Kushlan and Hancock 2005), bushes or trees (del Hoyo et al. 1992, Kushlan and Hancock 2005), usually over or surrounded by water (Kushlan and Hancock 2005). The species nests colonially in single- or mixed-species groups with the nests placed close or touching (Snow and Perrins 1998). Management information The species can adversely affect the trees and bushes it uses for nesting, which may lead to the abandonment of the colony site if it is not managed (Kushlan and Hancock 2005).
Threats
Large colonies nesting in urban areas are perceived as a public nuisance and may be persecuted (e.g. by disturbance to prevent colony establishment, removal or direct killing) (Kushlan and Hancock 2005). In its breeding range the species is threatened by wetland degradation and destruction such as lake drainage for irrigation and hydroelectric power production (Armenia) (Balian et al. 2002), and in some parts of its range it is susceptible to pesticide poisoning (organophosphates and carbamates) (Kwon et al. 2004). Utilisation The species is hunted and traded at traditional medicine markets in Nigeria (Nikolaus 2001).
Related state of the world's birds case studies
References
Balian, L. V.; Ghasabian, M. G.; Adamian, M. S.; Klem Jr, D. 2002. Changes in the waterbird community of the Lake Sevan-Lake Gilli area, Republic of Armenia: a case for restoration. Biological Conservation 106(2): 157-163.
Brown, L. H.; Urban, E. K.; Newman, K. 1982. The birds of Africa vol I. Academic Press, London.
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.
Hancock, J.; Kushlan, J. 1984. The herons handbook. Croom Helm, London.
IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012).
Kushlan, J. A.; Hancock, J. A. 2005. The herons. Oxford University Press, Oxford, U.K.
Kwon, Y. K.; Wee, S. H.; Kim, J. H. 2004. Pesticide Poisoning Events in Wild Birds in Korea from 1998 to 2002. Journal of Wildlife Diseases 40(4): 737-740.
Marchant, S.; Higgins, P. J. 1990. Handbook of Australian, New Zealand and Antarctic birds, 1: ratites to ducks. Oxford University Press, Melbourne.
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.
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
Butchart, S., Ekstrom, J., Malpas, L. & Symes, A.
Recommended citation
BirdLife International (2015) Species factsheet: Bubulcus ibis. Downloaded from http://www.birdlife.org on 04/04/2015. Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/04/2015.
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.
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