LC
Common Little Bittern Ixobrychus minutus



Justification

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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is not thought to 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 size has not been estimated owing to recent taxonomic splits. The European population is estimated at 63,100-111,000 pairs, which equates to 126,000-222,000 mature individuals (BirdLife International 2015). Europe forms approximately 20% of the global range so a very preliminary estimate of the global population would be 630,000-1,110,000 mature individuals although further validation of this estimate is needed. The population is therefore placed in the band 600,000-1,199,999 mature individuals.

Trend justification
The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2015). The European population is estimated to be stable (BirdLife International 2015).

Ecology

Behaviour Palearctic populations of this species undergo extensive post-breeding dispersal movements in all directions and are also fully migratory, travelling southward on a broad front (del Hoyo et al. 1992) between August and October and returning to the north from March to April (Kushlan and Hancock 2005). Other populations (e.g. in the tropics) are resident but may make partial migratory movements connected with fluctuations in water-level (del Hoyo et al. 1992). In the western Palearctic and India the species breeds mainly between May and July, breeding from June to February in South Africa, or in relation to the rains in tropical Africa (del Hoyo et al. 1992). It breeds singly or occasionally in small loose groups in favourable areas (del Hoyo et al. 1992) (e.g. 2-3 nests were spaced 50 m apart at the same pond, Africa) (Brown et al. 1982). When not breeding the species may be found singly, in pairs (Africa) (Brown et al. 1982), in small flocks of 5-15 individuals (Snow and Perrins 1998) (e.g. on migration) (del Hoyo et al. 1992), or roosting in groups of 30 individuals (Africa) (Brown et al. 1982). In most areas it is mainly a crepuscular feeder (del Hoyo et al. 1992, Kushlan and Hancock 2005) although it may be diurnal in some regions (e.g. South Africa) (Kushlan and Hancock 2005). Habitat The species is most common in freshwater marshes with beds of bulrushes Typha spp., reeds Phragmites spp. (Hockey et al. 2005) or other dense aquatic vegetation, preferably also with deciduous bushes and trees (del Hoyo et al. 1992) such as willow Salix spp. or alder Alnus spp. (del Hoyo et al. 1992, Kushlan and Hancock 2005). It may also occupy the margins of lakes, pools and reservoirs (del Hoyo et al. 1992), wooded and marshy banks of streams and rivers (Kushlan and Hancock 2005), desert oases, peat bogs (del Hoyo et al. 1992), wooded swamps, wet grasslands, rice-fields (del Hoyo et al. 1992), rank vegetation around sewage ponds (Hockey et al. 2005), and in places mangroves, the margins of saline lagoons (del Hoyo et al. 1992) and saltmarshes (Kushlan and Hancock 2005). Diet Its diet varies with region and season (del Hoyo et al. 1992) but it is essentially insectivorous and takes aquatic adult and larval insects such as crickets, grasshoppers, caterpillars (del Hoyo et al. 1992) and beetles (Kushlan and Hancock 2005). Other food items include spiders, molluscs, crustaceans (del Hoyo et al. 1992) (e.g. shrimp and crayfish) (Kushlan and Hancock 2005), fish, frogs, tadpoles, small reptiles and birds (del Hoyo et al. 1992). Breeding site The nest is constructed from reeds and twigs (del Hoyo et al. 1992) and is normally placed near open poolsin thick emergent vegetation (Kushlan and Hancock 2005) (such as beds of bulrushes Typha spp. or reeds Phragmites spp.) (Hockey et al. 2005) close to the surface of the water or up to 60 cm above it (Snow and Perrins 1998). Alternatively nests may be placed in low bushes or trees (e.g. alder Alnus spp. or willow Salix spp.) up to 2 m above water (del Hoyo et al. 1992, Kushlan and Hancock 2005). Preferred nesting sites are usually 5-15 m out from the shore in water 20-30 cm deep (Snow and Perrins 1998). The species usually nests singly but may nest in loose colonies in favourable habitats with neighbouring nests as close as 5 m apart (solitary nests are usually 30-100 m apart) (Kushlan and Hancock 2005). Nests are often reused in consecutive years (Kushlan and Hancock 2005).

Threats

The following information refers to the species's European range only: Since 1970, European populations have fallen, most likely due to habitat destruction and pollution, however these alone do not explain its decline. In Belgium, the species has suffered from pollution and the drainage of wetlands and in the Netherlands building construction has disturbed nesting habitat. High mortality during migration and in the wintering quarters has been attributed to the European declines. Droughts in Africa have led to desertification and loss of wetland areas, which extends the trans-Saharan crossing (Tucker and Heath 1994). Recreational activities such as fishing and swimming are also a threat as is the intensive commercial use of water areas (e.g. reed cutting, fish farming), river regulation measures and eutrophication (Bauer et al. 2006). The species may also be affected by fires (San-Miguel-Ayanz et al. 2009).

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: Although conservation measures in the European breeding grounds are unlikely to reverse declines in this species, wider-scale conservation actions should be taken, for example, the maintenance of reedy fringes to rivers and ditches. Habitat protection in Europe should be undertaken so that sufficient habitat exists for the species should habitat conditions in Africa become more favourable (Tucker and Heath 1994). Other measures should include: Sustainably managing river valleys and reed marshes, including the reduction of water pollution and fish overexploitation; Minimising disturbance from recreation at the breeding sites.

Acknowledgements

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


Recommended citation
BirdLife International (2022) Species factsheet: Ixobrychus minutus. Downloaded from http://www.birdlife.org on 17/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/08/2022.