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 has not been quantified, 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 population trend is difficult to determine because of uncertainty over the extent of threats to the species.
Behaviour There is no evidence that this species makes regular migratory movements (del Hoyo et al. 1996, Taylor and van Perlo 1998) although numbers may fluctuate throughout the year in some locations due to the dispersal of immatures and to nomadic behaviour in response to environmental conditions (del Hoyo et al. 1996, Taylor and van Perlo 1998, Hockey et al. 2005). The species is a strongly territorial breeder (del Hoyo et al. 1996) and undergoes a flightless moulting period lasting for c.3 weeks between August and November (Taylor and van Perlo 1998). Habitat It inhabits permanent and temporary swamps and marshes often at the edge of lakes, pools, rivers and streams, and also occurs in seasonally wet sugar-cane plantations and paddy-fields adjacent to natural marshes (del Hoyo et al. 1996, Taylor and van Perlo 1998). It requires shallowly flooded areas with mud and floating vegetation for foraging (del Hoyo et al. 1996, Taylor and van Perlo 1998), and shows a preference for habitats lined with reedbeds or dense species-rich vegetation (del Hoyo et al. 1996, Taylor and van Perlo 1998) with channels and runways linking patches of more open growth (Taylor and van Perlo 1998). For breeding the species shows a preference for seasonally inundated grasslands and sedge meadows (del Hoyo et al. 1996, Taylor and van Perlo 1998) with robust sedges and grasses c.50 cm or more in height (Taylor and van Perlo 1998). Diet Its diet consists of worms, crustaceans (e.g. crabs and crayfish), aquatic and terrestrial adult and larval insects, spiders, small fish, small frogs and some vegetable matter including seeds (del Hoyo et al. 1996). Breeding site The nest is a shallow cup of plant matter well concealed in aquatic vegetation, usually over water (del Hoyo et al. 1996).
Text account compilers
Butchart, S., Ekstrom, J., Malpas, L.
BirdLife International (2019) Species factsheet: Rallus caerulescens. Downloaded from http://www.birdlife.org on 22/05/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/05/2019.