Data Zone
Justification of Red List category
Ptilocichla falcata is endemic to Palawan (Philippines), where it is confined to intact lowland forests. In extent this habitat has declined moderately rapidly, and this is suspected to have had equivalent impacts on this species' population size. Declines are ongoing, with typhoons perhaps as big a threat now as logging, and from which no protected area is buffered. Accordingly it is listed as Vulnerable.
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%.
Ptilocichla falcata is endemic to Palawan in the Philippines, where it is known from sites spread across the island (Collar et al. 1999, eBird 2024).
It inhabits the floor and undergrowth of primary lowland forest, particularly near to streams, gullies and ridge-tops. It has been recorded up to 1,350 m on Mt Victoria (R. Hutchinson in litt. 2012) but the vast majority of records come from the island's extreme lowlands (below 400 m). Recent observations suggest that it may be very sensitive to habitat modification (Mallari et al. 2011).
The principal threat to this species is habitat loss and degradation. As a forest-dependent species, it is considered acutely vulnerable to even minor cases of forest loss and disturbance. Approximately 20-29% of this species' population is suspected to have been lost between 2011 and 2022 because of forest cover losses, which have principally been driven by logging and agricultural expansion (particularly plantations). In December 2021, Super Typhoon Odette (also known as Typhoon Rai) caused devastation across Palawan's lowland forests, and caused canopy cover on the island to reduce more than in any year since remote sensing data were analysed in detail (2000: Global Forest Watch 2024). Such intense typhoons are projected to become more frequent and intense with climate change (Holden and Marshall 2018); it could now be the case that climate change is now the biggest threat to this species and Palawan's other forest-dependent endemics.
Conservation Actions Underway
Occurs in one protected area, St Paul's Subterranean River National Park, as well as several other areas that are effectively protected (e.g. Iwahig Prison and Penal Farm). While protected areas have proven effective at preventing forest loss within the Philippines, typhoons pose an increasing risk to the island's forests.
20 cm. Medium-sized, shy, ground-dwelling babbler. Pale orange-rufous forehead, rufous-chestnut crown and hindneck. Blackish lores and area around eye. Bright rufous-chestnut wings and tail. Elongated feathers of back and rump black with broad white shaft-streaks. White throat with narrow black malar, rest of underparts blackish with prominent white shaft streaks. Dark bill and legs. Voice Loud whistled phrases such as tuu-wee tu-uu regularly repeated, interspersed with quieter warbling phrases. Hints Shy, inhabits damp areas, best located by song.
Text account compilers
Berryman, A.
Contributors
Allen, D. & Hutchinson, R.
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.