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

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	B1b(ii,iii)
2016	Near Threatened	B1ab(ii,iii)
2012	Near Threatened	B1ab(ii,iii)
2008	Near Threatened	B1a+b(ii,iii)
2004	Near Threatened
2000	Lower Risk/Near Threatened
1996	Data Deficient
1994	Data Deficient
1988	Lower Risk/Least Concern

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	13,100 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	5000-15000 mature individuals	poor	suspected	2023
Population trend	decreasing	poor	suspected	2016-2026
Rate of change over the past 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Generation length	2.9 years	-	-	-
Number of subpopulations	1-30	-	-	-

Population justification: The abundance and habitat associations of this species have been subject to some confusion. It is widely considered uncommon or rare (White and Bruce 1986, del Hoyo et al. 2006, Eaton et al. 2021), and Jones et al. (1995) failed to detect it at all at their point count stations (n=556; although many of these were not positioned in suitable habitat/elevation). However, it has since been observed at no fewer than 13 distinct blocks of forest (eBird 2023) and can therefore be considered likely to occur widely in suitable habitat, albeit at a low density. In total, c.2,000 km² of forest remains on Sumba (per Global Forest Watch 2023), but much of this is so heavily degraded that even a secondary forest-tolerant species such as this occurs in probably only a small percentage of this. Precautionarily, therefore, the species is suspected to number somewhere between 5,000 and 15,000 mature individuals, which assumes a somewhat arbitrary combined density/occupancy rate of  2.5-7.5 mature individuals/km². This estimate is considered to be of poor data quality and in some respects highly precautionary—a more refined estimate (as called for nearly 30 years ago by Jones et al. 1995) should be a key research priority.

Trend justification: The only identified threat to this species is habitat loss and degradation. In the ten years to 2022, forest cover on Sumba declined by c.5% (Global Forest Watch 2023, based on data from Hansen et al. [2013] and methods disclosed therein). Although this species is tolerant of edge habitat and lightly degraded forest (Eaton et al. 2021) this is considered to be the minimum rate of population reduction. This is because (1) habitat loss appears has been greatest in the island's lowlands, where this species is commonest; and (2) habitat degradation is suspected to have nonetheless had some impact. Consequently, Muscicapa segregata is suspected of having declined by 5-10% between 2012 and 2022, and precautionarily the same rate is suspected to occur in the future.

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
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 500 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation
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: Sumba Brown Flycatcher Muscicapa segregata. Downloaded from https://datazone.birdlife.org/species/factsheet/sumba-brown-flycatcher-muscicapa-segregata 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.