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 appears to be stable, 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 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.
The European population is estimated at 161,000-251,000 calling or lekking males, which equates to 323,000-501,000 mature individuals (BirdLife International 2015). Europe forms approximately 55% of the global range so a very preliminary estimate of the global population size is 590,000-910,000 mature individuals. The population is therefore placed in the band 500,000-999,999 mature individuals. This corresponds well with the latest global population estimate by Wetlands International (2015) of 100,000-1,000,000 individuals.
The overall population trend is estimated to be stable (Wetlands International 2015). The European population trend is unknown (BirdLife International 2015).
Behaviour This species is fully migratory (del Hoyo et al. 1996). Its Autumn dispersal to its wintering grounds beginning mid-July (Hockey et al. 2005), with the species returning to reoccupy its breeding grounds from April (del Hoyo et al. 1996). The species breeds in Europe from April to July and in the former USSR from May to July (del Hoyo et al. 1996). Early migrating birds (mainly juveniles) often moult in August during stops on migration, during which they become flightless for c.3 weeks (del Hoyo et al. 1996, Taylor and van Perlo 1998, Hockey et al. 2005). The species is territorial throughout both breeding and non-breeding seasons (del Hoyo et al. 1996) and is usually seen singly, in pairs or in family groups, although occasionally small groups of 2-4 individuals may forage together on migration (Taylor and van Perlo 1998). It normally roosts at night in thick vegetation and forages by day (although this behaviour is reversed when migrating) (Urban et al. 1986). Habitat The species inhabits similar habitats in both its breeding and winter ranges (Urban et al. 1986, del Hoyo et al. 1996, Taylor and van Perlo 1998), and generally requires very shallow water (less than c.15 cm deep, typically foraging in water less than 7 cm deep) that is rich in invertebrate food and is interspersed with stands of low vegetation cover (Taylor and van Perlo 1998). The species shows a preference for freshwater wetlands with a range of water depths or where water levels vary seasonally (del Hoyo et al. 1996), especially where these have a mixture of muddy, moist and shallowly flooded substrates (Urban et al. 1986, del Hoyo et al. 1996) and a dense covering of grass, sedges, rushes, Polygonum, Iris, Equisetum and other emergents, as well as trees (e.g. Acacia, Sesbania, Betula, Salix and Alnus) (del Hoyo et al. 1996). Suitable habitats include seasonal and permanent marshes and fens (del Hoyo et al. 1996, Taylor and van Perlo 1998), bogs, damp meadows, the edges of drainage ditches (Taylor and van Perlo 1998), swamps, seasonally flooded pans (Urban et al. 1986), pools in flooded grassland, grassy margins of reservoirs and lakes, slow-flowing rivers and sewage settling-ponds (Urban et al. 1986, del Hoyo et al. 1996, Taylor and van Perlo 1998). Diet The species is omnivorous, its diet consisting of small aquatic insect adults and larvae (e.g. Trichoptera, Odonata, Diptera, Coleoptera, Hemiptera, Lepidoptera and ants), earthworms, molluscs (del Hoyo et al. 1996, Taylor and van Perlo 1998), arachnids (del Hoyo et al. 1996) (e.g. spiders and water mites) (Taylor and van Perlo 1998) and small stranded fish (1-2 cm long) (Urban et al. 1986), as well as algae and the shoots, leaves, roots and seeds of Panicum, Oryza, Carex and Schoenoplectus (del Hoyo et al. 1996, Taylor and van Perlo 1998). Breeding site The nest is a thick-walled cup of plant matter, usually placed in thick vegetation near or over standing water, or alternatively in a tussock, or built up well above the water level (del Hoyo et al. 1996).
This species is vulnerable to changes in water levels, either through artificial wetland modification and drainage, or through climatic changes (Urban et al. 1986, del Hoyo et al. 1996). Numbers have declined over the past century in Europe due to wetland drainage (Urban et al. 1986, del Hoyo et al. 1996) and agricultural intensification (Hagemeijer and Blair 1997), and the species is threatened by wetland destruction in Africa (Urban et al. 1986, del Hoyo et al. 1996).
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. The promotion of low-intensity agriculture would likely also benefit this species. Research into the species's population dynamics and habitat requirements would inform future conservation measures.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Malpas, L.
BirdLife International (2020) Species factsheet: Porzana porzana. Downloaded from http://www.birdlife.org on 09/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/08/2020.