CR
Guam Rail Hypotaenidia owstoni



Taxonomy

Taxonomic note
Hypotaenidia owstoni (del Hoyo and Collar 2014) was previously placed in the genus Gallirallus.

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
D D D1+2

Red List history
Year Category Criteria
2019 Critically Endangered D
2016 Extinct in the Wild
2012 Extinct in the Wild
2010 Extinct in the Wild
2008 Extinct in the Wild
2004 Extinct in the Wild
2000 Extinct in the Wild
1996 Extinct in the Wild
1994 Extinct in the Wild
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency Low
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 4 medium
Extent of Occurrence breeding/resident (km2) 4
Number of locations 1 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 1-49 poor suspected 2019
Population trend Increasing suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations 1 - - -
Largest subpopulations 100 - - -
Generation length (yrs) 3.4 - - -

Population justification: Although individuals have been released on Guam and on Rota, there are unlikely to be any wild individuals remaining on Guam and the population on Rota is not yet considered to be self-sustaining. Sixteen birds were released on Cocos Island in 2010, with a further 10 in 2012 (The Lost Bird Project Inc. 2013). Evidence for breeding has been observed, and the bird is now found throughout the island, where it is considered to be self-sustaining. The population size on Cocos has not been estimated, but the area of the island is only c.38 hectares so the population size is likely to be extremely small (F. Amidon in litt. 2012, S. Medina in litt. 2017). The population is therefore placed in the band 1-49 mature individuals.

Trend justification: The species was formerly extinct in the wild and an introduced population has now been established on Cocos, where 16 individuals were released in 2010 and a further 10 in 2012 (The Lost Bird Project Inc. 2013). Although there are no population data from which to estimate a trend, evidence for breeding has been observed and the bird is now found throughout the island, so the population size is suspected to be increasing.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Guam (to USA) N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Guam (to USA) Guam National Wildlife Refuge
Guam (to USA) Cocos Island, Guam

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Pastureland suitable resident
Artificial/Terrestrial Plantations suitable resident
Forest Subtropical/Tropical Moist Lowland suitable resident
Grassland Subtropical/Tropical Dry major resident
Savanna Dry suitable resident
Shrubland Subtropical/Tropical Dry major resident
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Scale Unknown/Unrecorded Timing Scope Severity Impact
Future Majority (50-90%) Unknown Unknown
Stresses
Ecosystem degradation, Ecosystem conversion
Climate change & severe weather Storms & flooding Timing Scope Severity Impact
Future Whole (>90%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation, Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Boiga irregularis Timing Scope Severity Impact
Past, Likely to Return Whole (>90%) Rapid Declines Past Impact
Stresses
Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Past, Likely to Return Majority (50-90%) Rapid Declines Past Impact
Stresses
Reduced reproductive success, Species mortality
Natural system modifications Fire & fire suppression - Increase in fire frequency/intensity Timing Scope Severity Impact
Future Majority (50-90%) Slow, Significant Declines Low Impact: 4
Stresses
Ecosystem degradation, Reduced reproductive success, Species mortality
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Future Majority (50-90%) Unknown Unknown
Stresses
Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2020) Species factsheet: Hypotaenidia owstoni. Downloaded from http://www.birdlife.org on 12/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 12/07/2020.