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 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 may be moderately small to large, but it is not believed 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.
The European population is estimated at 980-1,400 calling or lekking males, which equates to 2,000-2,800 mature individuals or 3,000-4,200 individuals (BirdLife International 2015). Wetlands International (2015) estimates the population size of subspecies obscura to be 10,000-25,000 individuals and subspecies affinis at 1-10,000 individuals. Population estimates for the remaining four races are not known. National population estimates include 10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in China; 100-10,000 breeding pairs, 50-1,000 individuals on migration and < 50 wintering individuals in Japan; and 10,000-100,000 breeding pairs and 1,000-10,000 individuals on migration in Russia (Brazil 2009). The global population is here placed in the band 500,000-999,999 mature individuals, but this requires confirmation.
The population trend is difficult to determine because of uncertainty over the impacts of habitat modification on population sizes.
Behaviour African and Australasian populations of this species are non-migratory or only make local movements in response to seasonal habitat changes (del Hoyo et al. 1996). Those populations in Europe and Asia, however, appear to be fully migratory, most flying southward from late-August to October and returning to the northern breeding areas from March to May (del Hoyo et al. 1996, Taylor and van Perlo 1998). The species breeds in solitary pairs in the spring, usually nesting during or just after the wet season (where this occurs) (Urban et al. 1986, Langrand 1990, del Hoyo et al. 1996). It is usually a solitary species, but can be found in pairs or family groups, and sometimes forages in small groups of up to 10 individuals in non-breeding areas (Taylor and van Perlo 1998). The species forages diurnally but is most active in the early morning and late afternoon or evening (del Hoyo et al. 1996).
Habitat The species frequents similar habitats throughout its range and throughout the year, although its breeding areas are characterised by low, dense, tussocky or continuous vegetation such as flooded sedges and grasses (Urban et al. 1986, Langrand 1990, Marchant and Higgins 1993, del Hoyo et al. 1996, Taylor and van Perlo 1998). It inhabits freshwater, brackish or saline marshy wetlands, both inland and coastal (Australasia), permanent and temporary, with dense emergent and floating vegetation (especially reeds, rushes, sedges, tall dense grasses and Typha spp.) (Urban et al. 1986, Marchant and Higgins 1993, del Hoyo et al. 1996). Typical habitats include marshes, swamps, peat bogs, flooded meadows, damp grassland, seasonally flooded pans and depressions, tussocky grassland interspersed with patches of mud on the margins of open water (e.g. lakes and reservoirs), pools in sand-dunes, swampy creeks, rivers and streams, tall reedbeds (2-3 m high) with extensive mud, shallow puddles and Sesbania bushes, and occasionally salt-marsh (Urban et al. 1986, Marchant and Higgins 1993, del Hoyo et al. 1996, Taylor and van Perlo 1998). The species also frequents marshy artificial wetlands such as irrigated fields of crops (e.g. rice), sewage ponds, salt-works, farm ponds and dense grassy vegetation in rural residential areas (Urban et al. 1986, Marchant and Higgins 1993, del Hoyo et al. 1996, Taylor and van Perlo 1998). Although the species shows a preference for shallowly flooded areas, breeding birds may occupy grassland and sedges flooded to a depth of 30 cm and will occur on floating vegetation or in tall shrubs flooded to a depth of 2 m (Taylor and van Perlo 1998).
Diet Its diet consists predominantly of adult and larval insects (e.g. beetles, bugs, Odonata, stoneflies, caddisflies, flies and mosquitos), as well as annelids (up to 10 cm long), molluscs, small crustaceans (e.g. ostracods and copepods), small fish (up to 2 cm long), amphibians, and vegetative plant material and seeds (del Hoyo et al. 1996, Taylor and van Perlo 1998).
Breeding site The nest is a shallow cup or platform of vegetation placed close to water on a grass tussock or in soft grass, usually 4-60 cm above the water level (del Hoyo et al. 1996). Occasionally the nest may be floating or anchored to vegetation in water, or placed in or under low bushes (del Hoyo et al. 1996).
Management information Changes in water level during the nesting period should be avoided, cutting and burning of vegetation near the waters edge should be controlled and the maintenance of natural vegetation around fish ponds and rice-fields should be encouraged (Taylor and van Perlo 1998).
The species is threatened by degradation and loss of seasonal and ephemeral wetlands owing to drainage, overgrazing, cultivation (del Hoyo et al. 1996, Taylor and van Perlo 1998), reed-cutting, reed-burning and sudden changes in water levels caused by discharges from large dams (Taylor and van Perlo 1998). The species also suffers high mortality during migration from collisions with powerlines (Taylor and van Perlo 1998).
Conservation Actions Underway
CMS Appendix II. EU Birds Directive Annex I. Bern Convention Appendix II. There are currently no known conservation measures for this species in Europe.
Conservation Actions Proposed
The following information refers to the species's European range only: Key sites should be identified and protected and monitoring of populations introduced. Management techniques should include avoiding changes in water level during the nesting period; cutting and burning of vegetation near the waters edge should be controlled; natural vegetation around fish ponds and rice-fields should be maintained. Research into the species's population dynamics and habitat requirements would inform future conservation measures.
Text account compilers
Everest, J., Malpas, L., Butchart, S., Ashpole, J, Ekstrom, J., Elliott, N.
BirdLife International (2020) Species factsheet: Zapornia pusilla. Downloaded from http://www.birdlife.org on 19/02/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/02/2020.