• 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
-	-	A3c+4c; B1ab(i,ii,iii,iv,v)

Red List history

Year	Category	Criteria
2024	Vulnerable	A3c+4c; B1ab(i,ii,iii,iv,v)
2016	Vulnerable	A2c+3c+4c;B1ab(i,ii,iii,iv,v)
2012	Vulnerable	A2c+3c+4c;B1ab(i,ii,iii,iv,v)
2008	Vulnerable	A2c; A3c; A4c; B1a+b(i,ii,iii,iv,v)
2004	Vulnerable
2000	Vulnerable
1996	Endangered
1994	Endangered
1988	Lower Risk/Least Concern

Migratory status	not a migrant	Forest dependency	high
Land-mass type	shelf island	Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	17,300 km2	medium
Number of locations	6-20	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	5000-40000, 10000-30000 mature individuals	medium	estimated	2023
Population trend	decreasing	poor	inferred	2016-2027
Rate of change over the past 10 years/3 generations (longer of the two periods)	20-29%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	25-35%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	25-35%	-	-	-
Generation length	3.64 years	-	-	-
Number of subpopulations	3-10	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: A global population size has not been robustly estimated previously, but is here considered to probably fall between 5,000-40,000 mature individuals. In the Puerto Princesa Subterranean River National Park, Mallari et al. (2011) estimated densities in primary, advanced secondary, and early secondary of, respectively, 11.2, 4.8 and 1.5 birds/km².

The extent to which these densities are representative of suitable habitat across the island is unknown, but it is acknowledged that while the species has been recorded to 1,350 m, only in the extreme lowlands (<400 m) does it appear to be regularly encountered (eBird 2023), and it was at these elevations that Mallari et al. (2011) conducted their fieldwork.
The area of suitable forest within its elevational range is difficult to define, but is here estimated at a maximum of 3,500-5,000 km² (using a range of canopy cover and intactness scenarios from Hansen et al. [2013], Global Forest Watch [2024] and Grantham et al. [2020]), of which only 30-70% is here crudely estimated to be occupied, in an attempt to account for densities at different elevations, small isolated fragments unlikely to be occupied, unsuitable terrain etc. Applying densities spanning 4.8-11.2 mature individuals to these figures gives a broad range of (rounded) 5,000-40,000 mature individuals. An approximate midrange (10,000-30,000) is here chosen as the most likely.

Trend justification: Thought to be declining rapidly in response to habitat loss, with primary lowland forest bearing the brunt of Palawan's forest loss caused by logging, agricultural expansion and, in some years, typhoon damage.

In the past three generations (11 years: 2011-2022), forest cover within this species' mapped elevational range decreased by c.20%, with a considerable increase in 2022, when the effects of Super Typhoon Odette (also known as Typhoon Rai), which hit the island in December 2021, were first realised in remote sensing data. Losses have been most acute in the extreme lowlands (<200m), where losses were approximately 23-25%, and it is these elevations that are suspected to host the majority of this species' population. Given this species is highly forest dependent (see Mallari et al. 2011), rates of forest cover loss are suspected to be the best proxy for rates of population trend. Accordingly, over the past three generations, this species is suspected of having declined by 20-29%.

Rates of average forest loss have increased since c.2016. While a substantial amount was lost because of Super Typhoon Odette, even before this annual rates 2016-2021 were almost a third higher than in 2011-2016. Accordingly, if this doesn't cease or slow (and especially if another powerful typhoon hits in this window), then rates of forest cover loss, and hence population reduction, are suspected to be higher in the window 2016-2027. Similarly, future rates of decline over the next three generations (11 years: 2023-2034) are precautionarily suspected to be greater than the past. Accordingly, rates of population reduction between 2016 and 2027, and between 2023 and 2034, are suspected to be 25-35%.

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

Country/Territory	IBA Name
Philippines	Mount Mantalingahan
Philippines	Puerto Princesa Subterranean River Natural Park / Cleopatra's Needle
Philippines	Victoria and Anepahan Ranges

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 400 m	Occasional altitudinal limits	(max) 1350 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Shifting agriculture	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Rapid Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
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: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Rapid Declines		Medium Impact: 6
		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, Ecosystem conversion
Climate change & severe weather	Storms & flooding	Timing		Scope		Severity		Impact
		Ongoing		Whole (>90%)		Rapid Declines		High Impact: 8
		Stresses Ecosystem conversion, Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Falcated Wren-babbler Ptilocichla falcata. Downloaded from https://datazone.birdlife.org/species/factsheet/falcated-wren-babbler-ptilocichla-falcata 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.