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

Taxonomic note

Arcanator orostruthus (del Hoyo and Collar 2016) was previously placed in the genus Modulatrix following Dowsett & Forbes-Watson (1993); 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
-	-	C2a(i)

Red List history

Year	Category	Criteria
2021	Near Threatened	C2a(i)
2016	Vulnerable	B1ab(i,ii,iii,v)
2013	Vulnerable	B1ab(i,ii,iii,v)
2012	Vulnerable	B1ab(i,ii,iii,v)
2008	Vulnerable	B1a+b(i,ii,iii,v)
2004	Vulnerable
2000	Vulnerable
1996	Vulnerable
1994	Vulnerable
1988	Threatened

Migratory status	not a migrant	Forest dependency	high
Land-mass type	continent	Average mass	33 g

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	280,200 km2	medium
Area of Occupancy (breeding/resident)	10,532 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	1000-2499 mature individuals	poor	suspected	2021
Population trend	decreasing	medium	inferred	2016-2027
Rate of change over the past 10 years/3 generations (longer of the two periods)	10-20%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	10-20%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	10-20%	-	-	-
Generation length	3.48 years	-	-	-
Number of subpopulations	3-5	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The population in Mozambique was estimated by Dowsett-Lemaire (2010) to be 600-1,000 mature individuals on Mt Namuli, and up to 200 mature individuals on Mt Mabu. Since those surveys, large swathes of forest has been lost (J. Timberlake in litt. 2020), and the population in Mozambique is now likely to be <1,000 total individuals (B. Phalan in litt. 2020). This species was recently discovered on the Njesi Plateau in Mozambique (Jones et al. 2017), with the population there likely to be smaller than that on Namuli (B. Phalan in litt. 2020). The total population in the East Usambaras was considered to possibly only number a few pairs (Borghesio et al. 2008), and is still considered to be very rare (Neate-Clegg et al. 2021). The species in the Udzungwa Mountains may have undergone substantial declines owing to the effect of forest loss and degradation on its localised population (B. Phalan in litt. 2020), and the population may therefore be very small. In the absence of more conclusive data, the population size is tentatively suspected to fall into the band of 1,000-2,499 mature individuals. It is also tentatively assumed, based on available data, that the largest subpopulation contains <1,000 mature individuals.

Trend justification: The species's population is inferred to be declining in line with the fragmentation and degradation of mid-elevation forests within its range. Due to habitat loss (Dowsett-Lemaire, 2010; Timberlake, 2017), it is suspected to be declining at a rate of 10-20% over three generations (10.5 years [Bird et al. 2020]).

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

Country/Territory	IBA Name
Mozambique	Mount Mabu
Mozambique	Mount Namuli
Tanzania	East Usambara Mountains
Tanzania	Udzungwa Mountains
Tanzania	Udzungwa National Park

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Montane	major	resident
Altitude	900 - 2000 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		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Future		Minority (<50%)		Slow, Significant Declines		Low Impact: 3
		Stresses Ecosystem degradation, Ecosystem conversion
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
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation
Natural system modifications	Fire & fire suppression - Increase in fire frequency/intensity	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion

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Recommended citation
BirdLife International (2024) Species factsheet: Dapple-throat Arcanator orostruthus. Downloaded from https://datazone.birdlife.org/species/factsheet/dapple-throat-arcanator-orostruthus on 22/11/2024.
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 22/11/2024.