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 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 157,000-346,000 pairs, which equates to 314,000-693,000 mature individuals (BirdLife International 2015). Europe forms approximately 50% of the global range, so a very preliminary estimate of the global population size is 630,000-1,400,000 mature individuals. The population is therefore placed in the band 600,000-1,499,999 mature individuals.
The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2015). The European population trend is unknown (BirdLife International 2015).
Behaviour Western and southern populations of this species are mainly sedentary (Snow and Perrins 1998), whereas others are fully migratory, moving overland on a broad front between breeding and wintering grounds (del Hoyo et al. 1996). After mild winters the spring migration begins in late-February, otherwise it occurs from March to mid-April (Snow and Perrins 1998) or May (del Hoyo et al. 1996). In Europe and Russia the autumn migration occurs from August to December (del Hoyo et al. 1996, Snow and Perrins 1998). The species breeds in single pairs or small family groups (Snow and Perrins 1998) although large concentrations of breeding birds may occurring in extensive wetlands, with nests 20-50 m apart where population densities are high (Taylor 1998). After breeding the species may pause on passage in favourable habitats between early-July and early-September (Taylor 1998) to undergo a flightless wing-moult (Snow and Perrins 1998) that may last for c.3 weeks (Taylor and van Perlo 1998, Snow and Perrins 1998). Outside of the breeding season the species remains solitary (Taylor 1998, Snow and Perrins 1998), but may occasionally congregate into small groups of up to 30 individuals during the winter (Taylor 1998). The species regularly uses well-defined paths between favoured food sources within its habitat (Snow and Perrins 1998). Habitat The species requires muddy ground for foraging (del Hoyo et al. 1996) and shows a preference for shallow still or slow-flowing water (del Hoyo et al. 1996) 5-30 cm deep (Taylor 1998), surrounded by dense riparian, emergent, submergent or aquatic vegetation (del Hoyo et al. 1996). Breeding It breeds in reedbeds and other emergent vegetation in fresh and saline swamps, fens and marshes (del Hoyo et al. 1996, Taylor 1998) and at the fringes of open fresh or saline lakes (del Hoyo et al. 1996, Taylor 1998). Other habitats include clay pits, gravel pits, peat excavations (Taylor 1998), river oxbows and channels, damp meadows and rice paddy-fields (del Hoyo et al. 1996). Rather than occupying large uniform wet areas in larger habitats, the species shows a preference for wetlands that form a mosaic with drier patches and areas of trees (e.g. willow Salix spp. [Taylor 1998]) or other fringing scrub (Taylor 1998). Non-breeding On migration and in the winter the species frequents riverbanks (Urban et al. 1986), canals (Urban et al. 1986), gravel pits (del Hoyo et al. 1996), farm sewage outfalls (del Hoyo et al. 1996, Taylor 1998), marshy areas (Iceland) (del Hoyo et al. 1996), bracken on islands (del Hoyo et al. 1996, Taylor 1998), flooded blackberry Rubus spp. thickets (del Hoyo et al. 1996, Taylor 1998) and other very small wetland patches (del Hoyo et al. 1996). Diet The species is omnivorous, its diet consisting predominantly of animal matter (Snow and Perrins 1998) such as worms, leeches, molluscs, shrimps, crayfish, spiders, terrestrial and aquatic insects and larvae, amphibians (del Hoyo et al. 1996, Taylor 1998) (e.g. frogs, toads and newts) (Taylor 1998), fish, birds and mammals (del Hoyo et al. 1996). It also takes plant matter (especially during the autumn and winter) including shoots, roots, seeds, berries and fruits (del Hoyo et al. 1996). Breeding site The nest is a substantial cup of vegetation (del Hoyo et al. 1996, Taylor 1998) that is usually positioned in thick stands of reeds or rushes on the ground in or near water, or rarely on a tree stump or in the open (del Hoyo et al. 1996, Taylor 1998). Nests placed in water are built up if the water level rises (Urban et al. 1986).
The species is vulnerable to severe conditions (e.g. ice or severe floods) (del Hoyo et al. 1996, Taylor 1998). In some areas it suffers from habitat destruction through land reclamation and wetland drainage (Hagemeijer and Blair 1997).
Conservation Actions Underway
EU Birds Directive Annex II. There are currently no known conservation measures in place for this species within 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. Research into the species's population dynamics and habitat requirements would inform future conservation measures.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Symes, A., Taylor, J., Malpas, L.
BirdLife International (2020) Species factsheet: Rallus aquaticus. Downloaded from http://www.birdlife.org on 04/04/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/04/2020.