EN
Kiritimati Reed-warbler Acrocephalus aequinoctialis



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
- B2ab(ii,iii,v) B1ab(ii,iii,v)+2ab(ii,iii,v)

Red List history
Year Category Criteria
2019 Endangered B2ab(ii,iii,v)
2016 Endangered B1ab(i,iii,v)
2012 Endangered B1ab(i,iii,v)
2009 Endangered B1a+b(iii,v)
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern
Species attributes

Migratory status not a migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Distribution

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 7,600 medium
Extent of Occurrence breeding/resident (km2) 440
Number of locations 2-5 -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 2500-9999 poor suspected 2012
Population trend Decreasing poor suspected -
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 - - -
Percentage in largest subpopulation - - -
Generation length (yrs) 4.4 - - -

Population justification:

Pierce et al. (2007) recorded densities of up to 50 birds/km2 on Kiritimati and pairs reportedly occupy a territory of 1.8-2.3 ha, which coarsely equates to 100 mature individuals/km2. Combined, the islands of Kiritimati and Teraini have a land area of 336 km2, suggesting they could support a maximum of c.16,000-30,000 mature individuals. However, the species is absent from considerable areas of these two islands, likely due to unsuitable habitat, and occurs at lower densities, especially where invasive predators are present. Consequently, a global population of 2,500-9,999 mature individuals is suspected, though this may prove to be an overestimate and further surveys are required. This is equivalent to 3,750-14,999 individuals in total, rounded here to 3,500-15,000 individuals. Observations at Kiritimati in 2013 suggested that densities were highly variable, ranging from 0.1 to 1.1 birds per hectare and averaging 0.47 individuals per hectare of surveyed habitat (VanderWerf 2014, Pierce et al. 2015).

Trend justification: Population trends have not been empirically assessed, but the species has been extirpated from one island (Tabueran) in the 1970s, and threats within its extant range include introduced predators and habitat degradation driven by a variety of processes. However, on Kiritimati, monitoring has been ongoing since 2007, but no declines have been detected (R. Pierce in litt. 2016). The species is precautionarily assessed as having a small ongoing decline. Should the species be found not to be declining overall, it would warrant downlisting to a lower threat category.


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

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Kiribati Teraina (Washington Island)
Kiribati Kiritimati (Christmas Island)

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Shrubland Subtropical/Tropical Moist major resident
Altitude 0 - 20 m Occasional altitudinal limits  

Threats & impact
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%) Negligible declines Low Impact: 4
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Persecution/control Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
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
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Declines Medium Impact: 7
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Pluchea indica Timing Scope Severity Impact
Ongoing Whole (>90%) Negligible declines Medium Impact: 6
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus rattus Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Declines Medium Impact: 7
Stresses
Reduced reproductive success
Natural system modifications Fire & fire suppression - Increase in fire frequency/intensity Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2022) Species factsheet: Acrocephalus aequinoctialis. Downloaded from http://www.birdlife.org on 04/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/12/2022.