CR
Mariana Crow Corvus kubaryi



Taxonomy

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
A2bcde+3bcde+4bcde; C2a(ii) A2bcde+3bcde+4bcde; B1ab(i,ii,iii,v); C2a(i,ii); D A2bcde+3bcde+4bcde; B1ab(i,ii,iii,v); C1+2a(i,ii); D1+2

Red List history
Year Category Criteria
2018 Critically Endangered A2bcde+3bcde+4bcde; C2a(ii)
2016 Critically Endangered A2bcde+3bcde+4bcde; B1ab(i,ii,iii,iv,v); C2a(ii)
2015 Critically Endangered A2bcde+3bcde+4bcde;C2a(i,ii)
2013 Critically Endangered A2bcde+3bcde+4bcde;C2a(i,ii)
2012 Critically Endangered A2bcde+3bcde+4bcde;C2a(i,ii)
2010 Critically Endangered A2b,c,d,e; A3b,c,d,e; A4b,c,d,e; C2a(ii)
2009 Critically Endangered A2b,c,d,e; A3b,c,d,e; A4b,c,d,e
2008 Critically Endangered
2004 Endangered
2000 Endangered
1996 Critically Endangered
1994 Critically Endangered
1988 Threatened
Species attributes

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

Estimate Data quality
Extent of Occurrence (breeding/resident) 120 km2 medium
Number of locations 1 -
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size 50-249 mature individuals good estimated 2016
Population trend decreasing medium estimated 1988-2010
Rate of change over the past 10 years/3 generations (longer of the two periods) 80-100% - - -
Rate of change over the future 10 years/3 generations (longer of the two periods) 80-100% - - -
Rate of change over the past & future 10 years/3 generations (longer of the two periods) 80-100% - - -
Generation length 7.3 years - - -
Number of subpopulations 1 - - -
Percentage of mature individuals in largest subpopulation 100% - - -

Population justification: In 2013-14, Kroner and Ha (2017) recorded 46 breeding pairs with a potential eight more pairs in unsurveyed areas. They estimated the total population to be only 178 individuals. In 2012, Camp et al. (2015) estimated the population to be 81 individuals (95% CI = 30-202), and Faegre et al. (2016) estimated 50 breeding pairs in the 2015-2016 breeding season. Therefore, the population size is placed here in the range 50-249 mature individuals.

Trend justification: Surveys between 1982 and 2012 have revealed an extremely rapid population decline. The population is estimated to have declined by over 80% over the past three generations (22 years).


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Guam (to USA) extinct native yes
Northern Mariana Islands (to USA) extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Guam (to USA) Guam National Wildlife Refuge
Northern Mariana Islands (to USA) Rota

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Lowland major resident
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%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Persecution/control Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Species mortality
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Stresses
Indirect ecosystem effects, Ecosystem degradation
Climate change & severe weather Storms & flooding Timing Scope Severity Impact
Past, Likely to Return Majority (50-90%) Rapid Declines Past Impact
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
Ongoing Majority (50-90%) Very Rapid Declines High Impact: 8
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Dicrurus macrocercus Timing Scope Severity Impact
Ongoing Majority (50-90%) Very Rapid Declines High Impact: 8
Stresses
Competition
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Ongoing Whole (>90%) Very Rapid Declines High Impact: 9
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named species Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Varanus indicus Timing Scope Severity Impact
Ongoing Majority (50-90%) Very Rapid Declines High Impact: 8
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Reduced reproductive success, Species mortality
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Scale
Pets/display animals, horticulture international
Pets/display animals, horticulture international

Recommended citation
BirdLife International (2024) Species factsheet: Mariana Crow Corvus kubaryi. Downloaded from https://datazone.birdlife.org/species/factsheet/mariana-crow-corvus-kubaryi on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 23/12/2024.