Justification of Red List category
This species has a large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <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). 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 (>30% decline over three generations). The population size is unknown, but is not suspected to be sufficiently small to 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
There are no data available from which to estimate this species' population size, but was described as 'uncommon' by Eaton et al. (2021). In suitable habitat, however, it is regularly observed across its range (eBird 2022). The area of suitable habitat is very large (nearly c.40,000 km2; per Global Forest Watch 2022) and although no density data are available, it is considered highly unlikely that the number of mature individuals is fewer than 10,000.
Trend justification
The population is suspected to be declining slowly due to habitat loss at the lower elevations of its range (it has occasionally been recorded at c.600 m). In the three generations (14 years; Bird et al. 2020) to 2022, forest cover loss in its range was 3-6% (Global Forest Watch 2022, based on Hansen et al. [2013] and methods disclosed therein), depending on the assumptions used, and this is thought to have had only minor impacts on the population. The population size is therefore suspected of declining at a past and future rate of 1-9% over three generations.
Batrachostomus poliolophus is endemic to montane forests on Sumatra, Indonesia.
The species occurs in sub-montane primary forest and mixed pine forest between 1,200 and 2,000 m, with occasional records down to 600 m (Eaton et al. 2021).
In the three generations (14 years; Bird et al. 2020) to 2022, forest cover loss in its range was 3-7% (Global Forest Watch 2022, based on Hansen et al. [2013] and methods disclosed therein), and this is thought to have had minor impacts on the population. The majority of this forest loss has been caused by incursions into forest caused by agricultural expansion.
Conservation Actions Underway
None is specifically known. Much of its range lies in protected areas (UNEP-WCMC and IUCN 2022).
Conservation Actions Proposed
Understand the species' population density in available habitat. Continue to monitor habitat using remote sensing data.
Text account compilers
Berryman, A.
Contributors
Benstead, P., Bird, J., Eaton, J., Taylor, J. & Westrip, J.R.S.
Recommended citation
BirdLife International (2024) Species factsheet: Sumatran Frogmouth Batrachostomus poliolophus. Downloaded from
https://datazone.birdlife.org/species/factsheet/sumatran-frogmouth-batrachostomus-poliolophus 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.