• Summary
• Text account
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• Distribution map
• Reference and further resources

Justification of Red List category

Although the species has a restricted range, it is not believed to approach the thresholds for Vulnerable under the range size criterion which also requires a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation. The population trend is suspected to be stable, and hence does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified; hence it does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

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.

This species is restricted to the islands of Mangaia and Mitiaro, Cook Islands.

It inhabits a variety of habitats including reeds, gardens and woodland (Pratt et al. 1987).

On Mangaia, there are a variety of introduced species including the aggressive Common Myna Acridotheres tristis (numbering c.9,000 birds), cats and rats (both Pacific rat Rattus exulans and black rat R. rattus), and clearance for agriculture and browsing by goats causes habitat loss and fragmentation (Rowe and Empson 1996). However, the species remains common on both islands and may not be substantially affected by these threats. Additionally, forest extent on Mangaia is increasing overall due to the cessation of widespread pineapple cultivation (Thacker et al. 2022).

Conservation Actions Underway
The feasibility of eradicating A. tristis has been evaluated; it is thought possible at the cost of $100,000 and has the support of local people. The species was reportedly introduced to Atiu at the end of the 19th century, but there are no data on its current status here (Thibault and Cibois 2017) and the reasons for this introduction are unclear.

Conservation Actions Proposed
Carry out surveys to determine population size and trends. Implement the planned eradication of A. tristis on Mangaia. Train local people in animal husbandry techniques which will minimise negative impacts on the forest. Protect habitat on each island.

Text account compilers
Vine, J.

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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 23/11/2024.
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.