• Summary
• Text account
• Data table and detailed info
• Range map
• Resources

Taxonomic note
Previously listed as a subspecies of C. banyumas (del Hoyo and Collar 2016). Differs from C. whitei in: uniformly orange underparts in both sexes vs whitish belly and vent (3); lack of rufous tinge in tail (1); very short tail (allow 3, but probably 4), and evidently different voice (Gwee et al. 2019) (not assessed, but at least 1). The statement, however, in Eaton et al. (2016) about montanus having a ‘bright blue rump’ (also mentioned in HBW) is, on evidence in NHMUK, mistaken, and the amount on the blue-black on the chin is tiny. Differs from C. banyumas in strength and number of characters sufficient to be treated as specifically distinct, namely: darker upperparts in male (1); browner vs greyer upperparts in female (2); stronger orange breast in female (ns[1]); lack of rufous tinge in tail (1); narrower black chin in male (ns[1]); much shorter tail (allow 3, but probably 4); evidently different voice (Gwee et al. 2019) (not assessed, but at least 1). Previously and erroneously listed as C. (banyumas) coeruleatus in HBW and elsewhere (Peters 1931–1987), but the name coeruleatus is unavailable (Dickinson and Christidis 2014). Monotypic.

Taxonomic source(s)
Handbook of the Birds of the World and BirdLife International. 2022. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 7. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v7_Dec22.zip.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2022	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	does not normally occur in forest
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	387,000 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)	3-4%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	3-4%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	3-4%	-	-	-
Generation length	2.62 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: The population size of this species has not been estimated. It has a large range throughout the central highlands of Borneo, although it is typically described as local or rare (Mann 2008, Eaton et al. 2016).

Trend justification: There are no accurate trend data available for this species, although it is suspected of declining. Forest loss in this species' mapped range has been equivalent to c.3-4% over the past ten years (Global Forest Watch 2022, using data from Hansen et al. [2013] and methods disclosed therein). This species is thought to be moderately forest dependent and is likely to be declining at a rate broadly similar to that of forest loss.

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	400 - 1400 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Shifting agriculture	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Small-holder plantations	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion

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Recommended citation
BirdLife International (2025) Species factsheet: Dayak Blue Flycatcher Cyornis montanus. Downloaded from https://datazone.birdlife.org/species/factsheet/dayak-blue-flycatcher-cyornis-montanus on 05/01/2025.
Recommended citation for factsheets for more than one species: BirdLife International (2025) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 05/01/2025.