VU
Visayan Wattled Broadbill Sarcophanops samarensis



Justification

Justification of Red List category
This lowland forest specialist is listed as Vulnerable because extensive habitat loss has caused rapid population declines, which are projected to continue into the future.

Population justification
At one time evidently common given the number of historically collected specimens (BirdLife International 2001) but even by the mid-20th century, Rand and Rabor (1960) reported it to be rare on Samar and 'very rare' on Bohol. Brooks et al. (1995), however, considered it scarce on Bohol and commented that the species was 'unobtrusive and certainly under-recorded'. Allen (2020) considered it 'scarce' throughout its range, and a crude interpretation of citizen science data (eBird 2024) finds the species to be scarce, but also regularly recorded where it is found. Similarly, it was recorded at all eight watershed sites surveyed on Samar in 2002-2003 (Gruezo and Gonzalez 2014), although some of these have since been nearly totally denuded of suitable forest. It was notably not recorded in surveys of limestone forests in eastern Samar (Obeña et al. 2021). The population size of this species has not robustly been estimated, but BirdLife International (2001) considered it likely to be below 10,000 mature individuals (inferred from its listing under Criterion C1). The species appears to be confined to lowland forest and apparently tolerates little disturbance (BirdLife International 2001), although Allen (2020) did report it from 'well-developed secondary forest'. Within its geographic and elevational range there remains c. 5,000 km2 of suitable habitat, but only a proportion of this is likely to be occupied, since this estimate makes no consideration for forest integrity; habitat is also mostly distributed on Samar, where the species appears to be very scarce (Taylor et al. 2015, eBird 2024), despite increased observer effort in recent years. The population size is precautionarily suspected to number 2,500-9,999, following BirdLife International (2001) but surveys to confirm the species abundance, particularly on Samar/Leyte, are urgently needed.

Trend justification
No trend data are available for this species to robustly determine rates of decline, and so rates of forest cover loss is used as a proxy. Within its range, forest cover reduced by c.10–15% in the three generations (11 years) to 2023 (range determined using various assumptions regarding population abundance at different altitudes) (Global Forest Watch 2024, based on data from Hansen et al. [2013] and methods therein). While population trends in this highly forest-dependent species are thought to be closely tied to rates of forest cover loss, there are several reasons that these data in isolation may be (perhaps severely) underestimating rates of population decline. First, they make no attempt for forest degradation and modification, especially selective logging, which is thought to be rampant within this species' range (Apan et al. 2017, Grantham et al. 2020, Hutchinson 2021) as well as fragmentation. Second, the forest cover layers used by Global Forest Watch (2024) appear to overestimate the extent of suitable forest cover (in some instances evidently conflating highly degraded landscapes including plantations and parkland with forest), with rates of forest cover loss evidently skewed to areas of true natural forest likely to host this species. Thus on Samar/Leyte, where a majority of the species' population is thought to lie, the fastest rates of forest cover loss are occurring in and around Samar Island Natural Park (SINP), the only part of the island from which there are recent records (Taylor et al. 2015, eBird 2024). Accordingly, the rate of population reduction may be significantly more rapid than remote sensed land cover data suggest. Over the past three generations therefore, rates of population reduction are suspected to have fallen somewhere in the range of 15-35%, with a best and precautionary estimate of 25-35%. Future rates of reduction are harder to predict, but recent (2018-2023) rates of forest cover loss were consistent with the years before, such that a projection over the next three generations (11 years: 2024-2035) is thought to fall within the same range.

Distribution and population

Sarcophanops samarensis is endemic to the Eastern Visayas in the Philippines, where it is known from Samar, Leyte and Bohol (Collar et al. 1999, Taylor et al. 2015, eBird 2024).

Ecology

It is restricted to primary lowland forest, occurring up to 750 m (probably mostly <500 m), and appears to tolerate only minimal habitat disturbance (BirdLife International 2001). Some, if not all, areas are characterised by limestone outcrops. However, this apparent preference for forest growing on limestone karst may simply reflect the fact that forest remains in such areas because they are too rocky to cultivate and there is no water for drinking or irrigation.

Threats

The chief threat is lowland deforestation for timber extraction, shifting agriculture and, in particular, the removal of forests for plantations (particularly rubber). Forest cover reduced by c.10–15% in the three generations (11 years) to 2023 (range determined using various assumptions regarding population abundance at different altitudes) (Global Forest Watch 2024, based on data from Hansen et al. [2013] and methods therein), and most of this was concentrated on Samar and Leyte, particularly in and around Samar Island Natural Park (SINP), the only ostensibly protected area on Samar (see also Apan et al. 2017, Hutchinson 2021). Mining may also locally be a threat.

Conservation actions

Conservation Actions Underway
It occurs in one protected area, Rajah Sikatuna National Park on Bohol, and Samar Island Natural Park (SINP) on Samar. While the former designation appears affective at safeguarding lowland forests from clearance and degradation, the latter does not (Apan et al. 2017, Hutchinson 2021).

Conservation Actions Proposed
Identify and survey remaining tracts of lowland forest on Samar, Leyte and Bohol to establish its current distribution and population status. Conduct research into its ecological requirements, including tolerance of disturbed habitats. Propose additional key sites (following surveys) for establishment as protected areas. Ensure protection provided by the designation of Samar Island Natural Park is adequate at protecting lowland forests from incursions.

Identification

15 cm. Small, brightly-coloured passerine. Black throat and face. Green eye surrounded by large, prominent sky-blue wattle. Large, broad, pale blue bill. Purple crown, bordered by greyish nuchal collar. Purple mantle, becoming bright chestnut on rump and tail. Black wings with prominent white and lilac bar across tertials and secondaries. Lilac underparts becoming yellowish-white on lower belly. Female as male but gleaming white breast and belly. Juvenile duller. Voice Unknown. Hints Unobtrusive, joins mixed feeding flocks. Frequents understorey and middle layers of forest.

Acknowledgements

Text account compilers
Berryman, A.

Contributors
Hutchinson, R., Benstead, P., Bird, J., Taylor, J., Peet, N., Davidson, P. & Westrip, J.R.S.


Recommended citation
BirdLife International (2024) Species factsheet: Visayan Wattled Broadbill Sarcophanops samarensis. Downloaded from https://datazone.birdlife.org/species/factsheet/visayan-wattled-broadbill-sarcophanops-samarensis on 23/12/2024.
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 23/12/2024.