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

Taxonomic note
Saucier et al. (2019) describe the Spectacled Flowerpecker Dicaeum dayakorum from Borneo based on a single female specimen collected after a decade of observations and photographs of birds across the island. Their diagnosis reports:

Phenotypically assignable to the genus Dicaeum Cuvier, 1816, by short thin bill, specialized (bifid and semi-tubular) tongue morphology (Fig. 4), and a greatly reduced outermost primary feather… Diagnosable as distinct from other species of Dicaeum by the following combination of characters; (1) rows of white orbital feathers above and below the eye, forming thin, but conspicuous white arcs; (2) entirely gray and white plumage coloration with no evidence of carotenoid pigments in the adult plumage; (3) short distal bill length (6 mm from nares to bill tip). Field observations indicate that the eye-arcs of putative males are even more strongly expressed than in the female holotype. The strong white eye-arcs of D. dayakorum are unique in Dicaeidae, although traces of pale eye-arcs are known to be present in female and juvenile plumages of a few other species (e.g. D. monticolum, D. agile, D. pygmaeum). Red and yellow carotenoid pigments are evident in the plumage of most species of Dicaeum. The apparent lack of these pigments in the adult female holotype and field observations of putative adult males sets D. dayakorum apart from most of its congeners.

This new species is thus valid and is accepted by BirdLife.

Taxonomic source(s)
Handbook of the Birds of the World and BirdLife International. 2020. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 5. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v5_Dec20.zip.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2020	Data Deficient
2016	Not Recognised
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

Migratory status	unknown	Forest dependency	does not normally occur in forest
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	168,000 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	decreasing	-	inferred	-
Generation length	2.44 years	-	-	-

Population justification: The population size is unknown. It is suspected that the species could be present at low densities throughout remaining lowland forest on the island of Borneo, however the highly sporadic nature of sightings indicates perhaps that it is nomadic in addition to being difficult to detect (Saucier et al. 2019). With so few records to date, it is difficult to extrapolate that there is a large population, although  if further records confirm the persistent presence in multiple, widely spaced areas, a very small population size becomes less likely.

Trend justification: With only a handful of records from scattered locations in lowland Borneo, it is not possible to estimate a population trend. However the species appears to be highly dependent on largely intact lowland forest, supporting a range of mistletoe species (Saucier et al. 2019) and this habitat is being lost at a moderately rapid rate to both clearance for agriculture and to selective logging (Edwards et al. 2009, Saucier et al. 2019). In the vicinity of the sites at which the species has been recorded (Saucier et al. 2019), the rate of forest loss is estimated at a minimum of 7% in the past ten years (Global Forest Watch 2020). From this we can infer that there is a continuing decline in the number of mature individuals, as there is no evidence that the species can persist in heavily logged forest or in plantations (D. Edwards in litt. 2020, Saucier et al. 2019), but it is not possible to infer the rate of decline. If the distribution of mature mistletoe of certain species, likely a scarce resource (Saucier et al. 2019), is the key determinant of the occurrence of the species, then both the potential population and rate of decline will be very different to that predicted from forest loss data (D. Edwards in litt. 2020).

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

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	30 - 350 m	Occasional altitudinal limits	(max) 500 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Scale Unknown/Unrecorded	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Indirect ecosystem effects, Species disturbance, Ecosystem degradation, Reduced reproductive success
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Species disturbance, Ecosystem degradation, Reduced reproductive success

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Recommended citation
BirdLife International (2025) Species factsheet: Spectacled Flowerpecker Dicaeum dayakorum. Downloaded from https://datazone.birdlife.org/species/factsheet/spectacled-flowerpecker-dicaeum-dayakorum on 03/01/2025.
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 03/01/2025.