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CR
Mariana Crow Corvus kubaryi

IUCN Red List Criteria

Critically Endangered A2bcde+3bcde+4bcde;C2a(i,ii) 
Endangered A2bcde+3bcde+4bcde;B1ab(i,ii,iii,iv,v);C1+2a(i);D1+2 
Vulnerable A2bcde+3bcde+4bcde;B1ab(i,ii,iii,iv,v);C2a(i,ii);D 

IUCN Red List history

Year Category
2013 Critically Endangered
2012 Critically Endangered
2010 Critically Endangered
2009 Critically Endangered
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 -

Distribution

  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 90 medium
Number of locations 2 -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals 50-249 medium Estimated 2007
Population trend Decreasing medium -
Number of subpopulations 2 - - -
Largest subpopulation 48-247 - - -
Generation length (yrs) 7.3 - - -
Population justification: In 2008 only two males remained on Guam (Berry et al. in litt. 2008). On Rota, the population was estimated at 234 mature indiviuals in 1998 by Plentovich (2005) and there were only 60 confirmed pairs recorded in 2008 (Berry et al. in litt. 2008), hence the band 50-249 mature individuals seems appropriate. This equates to 75-374 individuals in total, rounded here to 70-400 individuals.
Trend justification: Surveys between 1982 and 2004 have revealed an extremely rapid population decline. The records of only 60 pairs in 2009 indicates that this decline has continued (Berry et al. in litt. 2008), though potentially at a slower rate. It is estimated to have declined by over 80% over the past three generations (22 years) owing to habitat loss, persecution and predation by invasive species (particularly brown tree snake on Guam).

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage Resident
Guam (to USA) Native Extant       Yes
Northern Mariana Islands (to USA) Native Extant Yes      

Important Bird Areas where this species has triggered the IBA criteria

Country/Territory IBA Name IBA link
Guam (to USA) Guam National Wildlife Refuge site factsheet
Northern Mariana Islands (to USA) Rota site factsheet

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Lowland major resident
Altitude 0 - 0 m 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 / Black Drongo (Dicrurus macrocercus) 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 / Brown Tree Snake (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 / Domestic Cat (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 / Unspecified rats (Rattus spp.) 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 Primary form used Life stage used Source Scale Level Timing
Pets Whole Adults and juveniles Wild International Non-trivial Recent

Recommended citation
BirdLife International (2014) Species factsheet: Corvus kubaryi. Downloaded from http://www.birdlife.org on 20/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/09/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Critically Endangered
Family Corvidae (Crows and jays)
Species name author Reichenow, 1885
Population size 50-249 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 90 km2
Country endemic? No
Links to further information
- Summary information on this species