NT
Ridgway's Rail Rallus obsoletus



Taxonomy

Taxonomic note
Rallus longirostris, R. crepitans and R. obsoletus (del Hoyo and Collar 2014) were previously lumped as R. longirostris following AOU (2000). Rallus elegans and R. tenuirostris (del Hoyo and Collar 2014) were previously lumped as R. elegans following AOU (2000). Sibley and Monroe (1990, 1993) included tenuirostris within R. longirostris.

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2020 Near Threatened C2a(i)
2016 Near Threatened C2a(i)
2014 Near Threatened C2a(i)
2012 Not Recognised
2008 Not Recognised
2004 Not Recognised
2000 Not Recognised
1994 Not Recognised
1988 Not Recognised
Species attributes

Migratory status not a migrant Forest dependency low
Land-mass type Average mass -
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 1,260,000 km2 medium
Severely fragmented? yes -
Population
Estimate Data quality Derivation Year of estimate
Population size 10000-19999 mature individuals poor estimated 2017
Population trend decreasing - inferred -
Generation length 2.11 years - - -
Percentage of mature individuals in largest subpopulation 1-89% - - -

Population justification:

The population of obsoletus in 2009-2011 was estimated at 1,167 individuals (range 954-1,426) using both survey data and model predictions of densities for unsurveyed sites (Liu et al. 2012a,b). Application of the same methodology to data from 2005-2008 yields an average population estimate of 1,719 individuals (range 1,169 to 2,172; Liu et al. 2012a). Form levipes has been estimated to number 633 pairs in the USA (Zembal et al. 2015) and c.240 pairs in Mexico (Eddleman et al. 1988; Ehrlich et al. 1992), while form yumanensis has been estimated to number 1,700-2,000 individuals (Ehrlich et al. 1992). A more recent population estimate, however, put the population at 6,629 individuals (95% CI: 4,859-8,399) in the Colorado River delta region of Mexico (Hinojosa-Herta et al. 2001). There are apparently no published population estimates for beldingi. The total population is therefore uncertain and whilst Partners in Flight (2019) estimate that the population currently exceeds 15,000 mature individuals, it is tentatively placed here within the band 10,000-19,999 mature individuals.

Trend justification: Data suggest that the population of obsoletus was relatively stable in 2005-2007, but declined by 51% between 2007 and 2008, followed by an apparent weak recovery in 2009-2011 (Liu et al. 2012a,b). Trends for other forms are less well known, but an overall decline is inferred.


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Mexico extant native yes
USA extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Mexico Bahía Lechuguilla
Mexico Estero Santa Cruz
Mexico Complejo Lagunar San Ignacio

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Mangrove Vegetation Above High Tide Level suitable breeding
Marine Intertidal Salt Marshes (Emergent Grasses) major breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Agro-industry farming Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Past, Unlikely to Return Minority (<50%) Slow, Significant Declines Past Impact
Stresses
Species mortality
Climate change & severe weather Storms & flooding Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Reduced reproductive success, Species mortality
Pollution Agricultural & forestry effluents - Herbicides and pesticides Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Residential & commercial development Commercial & industrial areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Food - human - - non-trivial recent
Sport hunting/specimen collecting - - non-trivial recent

Recommended citation
BirdLife International (2024) Species factsheet: Rallus obsoletus. Downloaded from https://datazone.birdlife.org/species/factsheet/ridgways-rail-rallus-obsoletus on 21/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 21/02/2024.