Squacco Heron Ardeola ralloides


Justification of Red List Category
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 direction is unclear however it is not thought to approach the thresholds for Vulnerable 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.

Population justification
The global population is estimated at 370,000-780,000 (Wetlands International 2015). The European population is estimated at 15,000-25,900 pairs, which equates to 30,000-51,700 mature individuals (BirdLife International 2015).

Trend justification
The overall population trend is unclear, some populations are thought to be stable and others may be increasing or decreasing (Wetlands International 2015). The European population trend is estimated to be stable (BirdLife International 2015).


Behaviour In the Palearctic this species is migratory and dispersive (del Hoyo et al. 1992), travelling on a broad front between breeding and wintering areas (Kushlan and Hancock 2005). African breeding populations are nomadic or sedentary however and make local dispersive movements to temporary wetlands following seasonal rains (Hockey et al. 2005). The species breeds from April to July in Eurasia and North Africa (the populations south of the Sahara breeding mainly during the rainy season) (del Hoyo et al. 1992) in single- or mixed-species colonies that can be up to 2,000 pairs in size (del Hoyo et al. 1992). After breeding Palearctic populations migrate south from August to November (del Hoyo et al. 1992, Kushlan and Hancock 2005), returning to the breeding colonies between February and May (Kushlan and Hancock 2005). The species feeds solitarily (Kushlan and Hancock 2005) or in small groups of 2-5 individuals during the breeding season (Kushlan and Hancock 2005) although in winter and on migration large feeding flocks may form (Kushlan and Hancock 2005) and in Africa resident populations may feed in parties of up to 20 individuals (Brown et al. 1982). The species is mainly crepuscular (del Hoyo et al. 1992), roosting by day and night in large (Kushlan and Hancock 2005) often mixed-species (Brown et al. 1982) groups in sheltered woods and reedbeds (these roosts may draw in herons feeding up to 80 km away) (Kushlan and Hancock 2005). Habitat The species inhabits permanent or temporary wetlands (Brown et al. 1982) showing a preference for fresh waters with abundant marsh vegetation (del Hoyo et al. 1992), reedbeds, nearby bushes, trees and scrub (Kushlan and Hancock 2005). Habitats frequented include swampy plains, river valleys, deltas, lakes, ponds, canals and ditches (del Hoyo et al. 1992) although rice paddyfields (del Hoyo et al. 1992, Kushlan and Hancock 2005) are now the principle habitat throughout much of its range (Kushlan and Hancock 2005). On migration (Kushlan and Hancock 2005) the species may also occur on estuaries, inshore reefs or islets (del Hoyo et al. 1992). It generally avoids dry habitats and those with very high rainfall (Kushlan and Hancock 2005), and usually breeds in the lowlands although it has bred on montane lakes up to 2,000 m (del Hoyo et al. 1992). Diet Its diet consists predominantly of larval insects although fish and amphibians (del Hoyo et al. 1992) (e.g. frogs and tadpoles) (Kushlan and Hancock 2005) up to 10 cm long, grasshoppers, beetles, butterflies, spiders, crustaceans, molluscs and exceptionally small birds may also be taken (del Hoyo et al. 1992). Breeding site The nest is a well-constructed platform (del Hoyo et al. 1992) usually placed less than 2 m (occasionally up to 20 m) high near or over water in reedbeds (del Hoyo et al. 1992) or in dense thickets of trees or shrubs (Kushlan and Hancock 2005) (e.g. of willow Salix spp. or poplar Populus spp.) (Hafner and Didner 1997), preferring nesting sites within 5 km of feeding areas (Kushlan and Hancock 2005). The species breeds in single- or mixed-species colonies that can be up to 2,000 pairs in size (del Hoyo et al. 1992), neighbouring pairs building nests 5-10 m apart (occasionally as close as 0.5 m) (Kushlan and Hancock 2005).


The greatest threat to this species is the loss and deterioration of natural and man-made freshwater habitats (e.g. through changes to flood regimes in rice paddyfields) and wet woodlands (e.g. through woodcutting and burning) (Hafner and Didner 1997). Utilisation The species is hunted and traded at traditional medicine markets in Nigeria (Nikolaus 2001).

Conservation actions

Conservation Actions Underway
The species is listed on Annex I of the EU Birds Directive, Annex II of the Bern Convention and Annex II of the Convention on Migratory Species, under which it is covered by the African-Eurasian Waterbird Agreement (AEWA).

Conservation Actions Proposed
The following information refers to the species's European range only: Reed marshes and freshwater habitats need to be sustainably managed, including the reduction of water pollution and fish overexploitation.


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

Recommended citation
BirdLife International (2021) Species factsheet: Ardeola ralloides. Downloaded from on 28/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 28/10/2021.