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

Taxonomic note
Previously included within G. brodiei but split (with borneense as a subspecies) following Gwee et al. (2019) who showed that the songs of sylvaticum in Sumatra and borneense in Borneo are very different from G. brodiei of mainland Asia (Himalayas to eastern China and south to Peninsular Malaysia) and pardalotum in Taiwan. From the limited specimen material available to the authors a single morphological character was identified to back up this strong vocal difference, with the neck-collar of Bornean and Sumatran taxa being white rather than rufous as in the continental and Taiwan taxa (photographs in the paper also suggest that Sumatran and Bornean taxa are much less obviously patterned on their upperparts). Two subspecies recognised.

Taxonomic source(s)
Handbook of the Birds of the World and BirdLife International. 2021. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 6. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2021	Least Concern
2016	Not Recognised
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	2,230,000 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	decreasing	-	suspected	2016-2026
Rate of change over the past 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Generation length	2.57 years	-	-	-
Number of subpopulations	2-100	-	-	-

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.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Brunei	extant	native	yes
Indonesia	extant	native	yes
Malaysia	extant	native	yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Montane	major	resident
Altitude	900 - 2700 m	Occasional altitudinal limits	280 - 2900 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Small-holder farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Small-holder plantations	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem conversion
Biological resource use	Fishing & harvesting aquatic resources - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation

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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.