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Taxonomic note

Symposiachrus verticalis and S. ateralbus (del Hoyo and Collar 2016) were previously lumped as Monarcha verticalis following Sibley & Monroe (1990, 1993).

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2023	Near Threatened	B1ab(iii)+2ab(iii); C2a(ii)
2016	Vulnerable	C2a(ii)
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	medium
Land-mass type		Average mass	22 g

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	187 km2
Area of Occupancy (breeding/resident)	129 km2
Number of locations	11-100	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	2500-7000 mature individuals	poor	suspected	2020
Population trend	decreasing	-	suspected	2016-2026
Rate of change over the past 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Generation length	3.36 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: The global population size has not been quantified, but the species is described as fairly common (Dutson 2011) and is precautionarily suspected to number 2,500-7,000 mature individuals (Clement et al. 2020).

Trend justification: Significant forest loss and associated considerable degradation on Djaul in the recent past is considered to be driving a slow but significant continuing decline in the population. Remote sensing data (Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein) indicate that in the ten years to 2021, forest loss in this species' range has been equivalent to c.2-3%, and this is thought to be continuing. Steeper declines in 2021 suggest that this could accelerate to a rate equivalent to c.4-5% over ten years in the future. Population declines are suspected to be roughly equivalent to the rate of tree cover loss. The current rate of population decline is therefore placed in the range 1-9% over ten years.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Papua New Guinea	extant	native	yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Shrubland	Subtropical/Tropical Moist	suitable	resident
Altitude	0 - 200 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
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 Ecosystem degradation

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Recommended citation
BirdLife International (2025) Species factsheet: Djaul Monarch Symposiachrus ateralbus. Downloaded from https://datazone.birdlife.org/species/factsheet/djaul-monarch-symposiachrus-ateralbus on 07/01/2025.
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 07/01/2025.