VU
Rarotonga Monarch Pomarea dimidiata



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
- - D1+2

Red List history
Year Category Criteria
2018 Vulnerable D1+2
2016 Vulnerable D1+2
2012 Vulnerable D1+2
2008 Endangered D1
2006 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 23 g
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 1,000 medium
Number of locations 2 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 500 good observed 2016
Population trend Increasing good observed -
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 2 - - -
Largest subpopulations 1-89 - - -
Generation length (yrs) 6.9 - - -

Population justification: The population was estimated at 306 in August 2004, but a subsequent series of devastating cyclones in early 2005 lead to a decline, especially on Rarotonga. The total population began to increase in 2007 due to good recruitment on Atiu (where 30 birds were transferred in 2001-2003) and a stable population on Rarotonga. In 2011 the population was estimated at c.380 birds, including 69 yearlings (Robertson et al. 2011, H. Robertson in litt. 2011), suggesting a population of c.310 mature individuals. The number of mature individuals is now estimated at 500 (H. Robertson in litt. 2016).

Trend justification: The population has grown rapidly owing to intensive management, particularly predator control, and the transfer of 30 young birds to Atiu Island in 2001-2003. The population on Rarotonga declined as a result of five cyclones in one month in early 2005, and subsequent poor breeding in 2005-2006; however, the population has now been increasing since 2007, owing to intensive conservation action.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Cook Islands N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Cook Islands Takitumu Conservation Area, Rarotonga
Cook Islands Atiu

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Lowland major resident
Altitude 10 - 250 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Past, Likely to Return Majority (50-90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Climate change & severe weather Storms & flooding Timing Scope Severity Impact
Future Whole (>90%) Rapid Declines Medium Impact: 6
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Boiga irregularis Timing Scope Severity Impact
Future Whole (>90%) Rapid Declines Medium Impact: 6
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Ongoing Whole (>90%) No decline Medium Impact: 6
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Herpestes javanicus_old Timing Scope Severity Impact
Future Whole (>90%) Rapid Declines Medium Impact: 6
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus rattus Timing Scope Severity Impact
Ongoing Whole (>90%) No decline Medium Impact: 6
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Future Whole (>90%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Future Whole (>90%) Rapid Declines Medium Impact: 6
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Problematic native species/diseases - Urodynamis taitensis Timing Scope Severity Impact
Ongoing Whole (>90%) Unknown Unknown
Stresses
Species mortality

Recommended citation
BirdLife International (2021) Species factsheet: Pomarea dimidiata. Downloaded from http://www.birdlife.org on 19/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/01/2021.