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

Justification of Red List category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence under 20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (under 10,000 mature individuals with a continuing decline estimated to be over 10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (over 30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.

Population justification
The global population size has not been quantified, but the species is reported to be locally common on Sumatra, uncommon on Borneo, locally not uncommon on Java and Bali, common on Timor, less common on Lombok and locally common on Palawan (MacKinnon and Phillipps 1995, Coates et al. 1997, Kennedy et al. 2000). National population sizes have been estimated at c.10,000-100,000 breeding pairs in China and c.10,000-100,000 breeding pairs in Taiwan (Brazil 2009). This species is considered to have a medium dependency on forest habitat, and tree cover is estimated to have declined by 2.7% within its mapped range over the past 10 years (Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein). Therefore, as a precautionary measure, it is tentatively suspected that this loss of cover may have led to a decline of between 1-19% in the species' population size over the same time frame.

Trend justification
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Text account compilers
Rutherford, C.A.

Recommended citation
BirdLife International (2024) Species factsheet: Brownish-flanked Bush-warbler Horornis fortipes. Downloaded from https://datazone.birdlife.org/species/factsheet/brownish-flanked-bush-warbler-horornis-fortipes on 26/11/2024.
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 26/11/2024.