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

Taxonomic note
See A. vaughani. Monotypic.

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
-	-	D2

Red List history

Year	Category	Criteria
2022	Vulnerable	D2
2016	Vulnerable	D2
2012	Vulnerable	D2
2008	Vulnerable	D2
2004	Vulnerable
2000	Vulnerable
1994	Not Recognised
1988	Not Recognised

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	80 km2	medium
Area of Occupancy (breeding/resident)	80 km2
Number of locations	1	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	4000-8600 mature individuals	medium	estimated	1992
Population trend	stable	poor	estimated	-
Generation length	5.46 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: Estimates over the past three decades have been broadly congruent. In 1987, the population was estimated to number c.13,000 individuals (value adjusted to correct island area) and available habitat was apparently saturated (Graves 1992). In 1991-1992 surveys, using a different technique, 11,000 individuals were estimated, a number also thought true in 2003 and 2011 (M. Brooke in litt. 2007-2012). In 2015, the population at 25 point count locations was extrapolated to the area of suitable habitat, equal to 7,194 (5,875-8,593) individuals (Bond et al. 2019a). Because the latter estimate was based on detectability distances that were not empirically determined, these results are treated with some caution, although their proximity to earlier data suggest that the population size of this species is between 6,000 and 13,000 individuals, thought equivalent to c.4,000-8,600 mature individuals.

Trend justification: Although direct comparison is hampered by methodological differences, count data between 1987 and 2015 are comparable (Graves 1992, Brooke and Jones 1995, Bond et al. 2019a) and do not indicate any decline. Since 2015, there is no identified threat that may have caused a reduction.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Pitcairn Islands (to UK)	extant	native	yes

Country/Territory	IBA Name
Pitcairn Islands (to UK)	Henderson Island

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Dry	major	resident
Altitude	0 - 330 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus exulans	Timing		Scope		Severity		Impact
		Ongoing		Whole (>90%)		Negligible declines		Medium Impact: 6
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus norvegicus	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Very Rapid Declines		Medium Impact: 7
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus rattus	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Very Rapid Declines		Medium Impact: 7
		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%)		Very Rapid Declines		Medium Impact: 7
		Stresses Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Henderson Island Reed-warbler Acrocephalus taiti. Downloaded from https://datazone.birdlife.org/species/factsheet/henderson-island-reed-warbler-acrocephalus-taiti on 23/11/2024.
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 23/11/2024.