Data Zone
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. It is also assumed to have a population that 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). Although 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 ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
Described as uncommon throughout its range (van Marle and Voous 1988, Mann 2008, Eaton et al. 2016). No density estimates are available for this species (or any of its Asian congeners) and so a population size has not been estimated. Given the size of its range however, it is not considered likely to approach the thresholds (<10,000) for listing as threatened.
Trend justification
Approximately 6-7% of forest in this species's range was lost 2011-2020 (Global Forest Watch 2020). This species's habitat requirements are poorly known but all known sightings are from undisturbed primary forest (with absence in surveyed areas of secondary forest and cultivation [Puan et al. 2015]) and is hence suspected to be declining at a rate of 5-10% over 3 generations. It therefore does not approach the rates of decline required for listing as threatened.
The nominate subspecies is endemic to Sumatra, Indonesia. Subspecies borneeensis occurs on Borneo, where recorded in Sabah and Sarawak (Malaysia), Brunei Darussalam, and Kalimantan.
Occurs in montane and submontane forest, at 900-2,700 m (Eaton et al. 2016); exceptionally recorded down to 280 m (Thompson 1966, Puan et al. 2015). Absent from areas of secondary forest and cultivation (Puan et al. 2015). Active and vocal during the day (and also at night), this species occurs in the canopy, feeding on insects and small birds (Smythies and Davison 1999). Its breeding season and ecology are wholly unknown (van Marle and Voous 1988, Mann 2008) but are presumably similar to G. brodiei.
Because of this species's elevational limits (not usually occurring below 900 m [Eaton et al. 2016]), it is not affected by the rapid deforestation rates that beset the Sundaic region's lowland forests. There is, however, a specimen record from 280 m (Thompson 1966), and so lowland forest loss may be causing declines in isolated areas where this species descends to lower elevations. The construction of roads and tracks on Borneo is increasingly opening up access to higher elevations, which are then cleared for agriculture and timber. As a strictly forest-dependent species, it is undoubtedly affected by even minor rates of deforestation.
Conservation Actions Underway
Occurs in numerous protected areas.
Conservation Actions Proposed
Continue to monitor habitat loss using remote sensing data. Undertake surveys to establish density and global population size estimates.
15-17 cm. Small, rotund owl. Speckled crown, streaked belly, buff-barred upperparts, white-and-black immitation of a face on the nape. Voice A distinctive, soft, even-pitched iteration of seven notes: "toot, toot-toot, toot, too-too-too".
Text account compilers
Berryman, A.
Recommended citation
BirdLife International (2024) Species factsheet: Sunda Owlet Glaucidium sylvaticum. Downloaded from
https://datazone.birdlife.org/species/factsheet/sunda-owlet-glaucidium-sylvaticum on 01/12/2024.
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 01/12/2024.