Data Zone
Justification of Red List category
This species has a very restricted range where habitat degradation is ongoing. It is therefore assessed as Near Threatened.
Population justification
This species is described as common and widely distributed throughout Nauru (Buden 2008). Buden (2008) estimated the population at 5,000 individuals, roughly equivalent to 3,000 mature individuals.
Trend justification
Habitat loss and degradation in the past may not have majorly affected this species and it can utilise any scrubby vegetation (Buden 2008). However, a number of plausible threats remain and in the absence of an up-to-date evaluation of the population, the population trend is considered unknown.
Acrocephalus rehsei is endemic to the tiny island of Nauru, in the western Pacific Ocean.
It occurs at highest densities in remnant forest on the steep sides of the island escarpment, but is also frequently found in gardens and rural areas in coastal areas and in previously mined, but now regenerating areas of scrub, thickets, and remnant forest patches on the central plateau (B. Fletcher in litt. 1995, Buden 2008). In coastal areas, it forages for insects in the crowns of coconut trees (B. Fletcher in litt. 1995) and has been observed apparently gleaning insects from foliage in shrubs and among the branches of small trees as well as sallying from a low perch and apparently foraging on the ground in open, sparsely vegetated areas (Buden 2008). Stephen (1936) reported this species nesting on the ground; however Buden (2008) observed disused nests 2-8 m high in shrubs and trees.
Habitat loss and degradation in the past may not have majorly affected this species as it is able to colonise regenerating areas (B. Fletcher in litt. 1995, Buden 2008). However, nearly 80 years of phosphate mining has caused devastating environmental damage to the island (Anderson 1992), and although extraction is now carried out on a smaller scale, it is ongoing and continuing further around the island and deeper inland (Morris 2022). Habitat disturbance has also been caused by construction of infrastructure for refugee accommodation (Morris 2022). There is no information on other possible threats, such as predation by introduced rats Rattus spp. which have caused severe declines in other small-island Acrocephalus species. Buden (2008) reports an apparent incident of a nest that may have been predated by rats, but this is purely speculative and the species remains common. The species might be at risk from cyclones given its small range, the impact of which may increase with ongoing erosion and sea-level rise (Morris 2022), however its broad habitat preferences suggest a high resistance to such events.
Conservation Actions Underway
None is known.
15 cm. Medium-sized, drab warbler with thin, straight bill. Greyish-olive above, off-white below with white eyebrow. Similar spp. No other passerines on the island. Voice Unreported, but presumably has the chuck call note shared by most Pacific island reed-warblers.
Text account compilers
Vine, J.
Contributors
Buden, D., Cibois, A. & Fletcher, B.
Recommended citation
BirdLife International (2024) Species factsheet: Nauru Reed-warbler Acrocephalus rehsei. Downloaded from
https://datazone.birdlife.org/species/factsheet/nauru-reed-warbler-acrocephalus-rehsei 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.