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

Taxonomic note

Symposiachrus brehmii (del Hoyo and Collar 2016) was previously listed as Monarcha brehmii.

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
2022	Near Threatened	B1b(iii)
2016	Endangered	B1ab(ii,iii,v)
2012	Endangered	B1ab(ii,iii,v)
2008	Endangered	B1a+b(ii,iii,v)
2004	Endangered
2000	Endangered
1996	Endangered
1994	Endangered
1988	Threatened

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	3,600 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	20000-80000, 20000-40000 mature individuals	poor	inferred	2020
Population trend	decreasing	poor	suspected	2016-2027
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	3.72 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: Previously, the population was suspected to number 2,500-9,999 (BirdLife International 2016) although this is now considered an underestimate. This species is typically described as rare (Pratt and Beehler 2015), but eBird (2022) data suggest that it may at least locally be more common, with eight individuals encountered on one 2.5-km checklist, although generally only 2-3 are encountered on such transects. Most habitat surveyed appears to host this species (eBird 2022). Other Symposiachrus typically occur at a high density, numbering 100-200 birds/km² (e.g. Marsden et al. 1997, Poulsen 1998). Using the global landcover 2 estimate of forest cover for the island (closed to open broadleaved evergreen or semi-deciduous forest) and excluding fragments smaller than 1 km² results in an area classified as forest habitat of 1,572 km². Even precautionarily assuming that S. brehmii occurs at a density 20-40% of congeners, the population is here inferred to number 30,000-120,000 birds, or c.20,000-80,000 mature individuals, with a best estimate (20,000-40,000) at the lower end of this.

Trend justification: No direct assessment of the rate of population change has been made. This species is considered to be highly forest dependent. There has been a slow rate of forest cover loss, up to 4% over the past three generations (data from Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein), and this is suspected to be causing broadly equivalent reductions in population size of this species, set here to 1-9% over three generations (11.1 years; Bird et al. 2020).

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

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Subtropical/Tropical Heavily Degraded Former Forest	suitable	resident
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 600 m	Occasional altitudinal limits

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%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation

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Recommended citation
BirdLife International (2024) Species factsheet: Biak Monarch Symposiachrus brehmii. Downloaded from https://datazone.birdlife.org/species/factsheet/biak-monarch-symposiachrus-brehmii on 22/12/2024.
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 22/12/2024.