• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note
This species was initially considered a subspecies of A. vaughani; unlike the latter (which does not sing), however, it is a good singer, and differs also in measurements, in plumage coloration, in showing no tendency towards leucism, and in DNA (Cibois et al. 2011a). Two subspecies are recognized.

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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2024	Least Concern
2016	Near Threatened	B1b(v); D2
2012	Near Threatened	B1ab(v);D2
2008	Near Threatened	D2
2004	Near Threatened
2000	Lower Risk/Near Threatened
1994	Lower Risk/Least Concern
1988	Lower Risk/Least Concern

Migratory status	not a migrant	Forest dependency	low
Land-mass type		Average mass	22 g

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	1,600 km2	medium
Area of Occupancy (breeding/resident)	120 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	stable	poor	suspected	1998-2008
Generation length	3.1 years	-	-	-
Number of subpopulations	2	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The global population size has not been quantified, but the species is described as common across both islands in its range (McCormack 1997, del Hoyo et al. 2006, Thibault and Cibois 2017, eBird 2023).

Trend justification: There are no data on population trends. Although introduced species and habitat loss and fragmentation are plausible threats, the species occurs in a wide variety of habitats and seemingly remains very common throughout both islands. Additionally, forests on Mangaia have been regenerating in spite of these threats, with forest extent (primarily secondary forest, but also primary and Barringtonia forests) substantially increasing between 1996 and 2019 due to the cessation of widespread pineapple cultivation (Thacker et al. 2022). eBird records on Mangaia also do not suggest the species has become substantially less common (eBird 2023). In the absence of evidence for any declines or substantial threats, the species is here suspected to be stable.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Cook Islands	extant	native	yes

Country/Territory	IBA Name
Cook Islands	Mangaia
Cook Islands	Miti'aro Island

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Rural Gardens	suitable	resident
Forest	Subtropical/Tropical Moist Lowland	suitable	resident
Shrubland	Subtropical/Tropical Moist	suitable	resident
Wetlands (inland)	Bogs, Marshes, Swamps, Fens, Peatlands	suitable	resident
Altitude	0 - 180 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Small-holder farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Acridotheres tristis	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		No decline		Low Impact: 5
		Stresses Species disturbance, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Capra hircus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Felis catus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus exulans	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus rattus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Reduced reproductive success, Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Cook Islands Reed-warbler Acrocephalus kerearako. Downloaded from https://datazone.birdlife.org/species/factsheet/cook-islands-reed-warbler-acrocephalus-kerearako 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.