Justification of Red List Category
This species is known from only one locality, where habitat continues to decline in extent and quality, such that its tiny population must certainly be dwindling. Because of this alarming situation, it is classified as Critically Endangered.
The population size is likely to be extremely low (possibly fewer than 100 birds), given the tiny area of remaining habitat. An initial population estimate of 56-205 individuals (BirdLife Indonesia 2007) has not increased despite more recent surveys accessing a larger potential area. The most recent population estimate is between 92-255 individuals in total (Burung Indonesia 2009) and so is placed in the band 50-249 mature individuals. There is the potential for the population to be even lower than this, as these estimates are based on density estimates created from very few presence points (Burung Indonesia 2009).
This species is assumed to be declining owing to on-going forest loss within its restricted range. In 2009, reports suggested that numbers of this species were in serious decline owing to forest clearance (Sykes 2009). The species was not detected in 2015 at the most northwesterly and most southerly points where it was present in 2009, where habitat has been further degraded and from which the range is inferred to be continuing to decline (Martin 2018).
This species is endemic to the island of Sangihe, north of Sulawesi, Indonesia. Until its rediscovery in 1995, it was only known from one historical specimen collected in the late 19th century. It occurs around the Sahendaruman crater in the south of the island, and may have previously occurred on Gunung Awu (the type locality is given as a village on the slope of that volcano, but there are no further records). Sangihe Whistler occurs only within a highly restricted elevational band in primary forest along the ridgeline that form the crater rim. Habitat-association modelling indicated that the total area of suitable habitat for the species is only c.6 km2 (Martin 2018). Small-scale clearance and degradation for agriculture and hunting mammals are continuing within this range.
The species is resident in the upper parts of the montane forest at Sahendaruman Crater, between 600 m and 1,040 m. It occurs singly and perhaps more frequently in small groups, in the middle and upper forest storeys and also in dense rattan undergrowth. High canopy cover and the presence of large trees are key structural predictors of the presence of the species (Martin 2018). A habitat suitability model predicted that all suitable habitat is restricted to the vicinity of the ridgetop and outlying ridges, with records since 2009 only occurring above 705 m (Martin 2018), despite earlier records down to 575 m (Riley 2002).
Original forest on Sangihe has been almost completely converted to agriculture. The largest habitat tract in which the species has been observed is only 225-340 ha in size and undergoing clearance by shifting cultivators in its lower reaches. For example, development of new plantations have continued around the Sahendarmang region (W. Pangimangen in litt. 2020). In 2009, it was reported that new government initiatives to plant alien tree species were resulting in the clearance of native forest (Sykes 2009). At first, planting was restricted to areas below 500 m; however, more recent reports indicate that planting is now taking place at higher elevations, in areas at 700-900 m (Sykes 2009). Having a montane distribution that is close to the maximum altitude within its range, this species is potentially susceptible to climate change (BirdLife International unpubl. data).
Conservation Actions Underway
The Gunung Sahendaruman Protection Forest encloses an area of 3,500 hectares, but forest of good condition is only found within an area of 1,300 hectares (Martin 2018). Within this, only a proportion is suitable for the species (Martin 2018). The Protection Forest is largely mixed agriculture and spice tree plantations, which does not satisfy the designated role of the area to maintain environmental services (water, land stability). Some forest is additionally protected as watershed for a hydroelectric scheme in the Kentuhang valley, though this is within the Protection Forest boundary. Since 2014, the day-to-day management of the Protection Forest is under the jurisdiction of the provincial government, and a Forest Management Unit was established in 2017 to undertake this duty.
Burung Indonesia have been conducting periodic monitoring of the Critically Endangered species around the Sahendaruman crater with support from Vogelbescherming (Burung Indonesia 2009; Fauzan and Bashari 2016).
In 2015 habitat associations were investigated to model the current extent of suitable habitat and evaluate the potential for habitat restoration in different locations on the island (Martin 2018). Burung Indonesia developed a series of community-based Village Resource Management Agreements (VRMAs) at key villages around the crater during the Global Environment Fund-supported conservation project between 2002 and 2006, which successfully slowed rates of forest clearance (BirdLife Indonesia 2007). Between 1995 and 2005 the 'Action Sampiri'-project worked for biodiversity conservation in Sangihe and Talaud, conducting fieldwork, establishing conservation awareness programmes (including village and school meetings, distribution of leaflets etc.) and developing ideas for future land-use through agreements between interested parties (local people, local government, forestry officials and timber companies). Sangihe is a priority site for the Critical Ecosystem Partnership Fund, and Burung Indonesia are the Regional Implementation Team for the Wallacea Hotspot. A project conducting a forest cover survey through ground-truthing remote sensed forest cover maps began in 2017, and an extension of the VRMA programme is planned.
There have been proposals to change the designation of the Protection Forest on Gunung Sahengbalira to the more strictly controlled wildlife reserve; however, this is considered to have the potential to greatly deteriorate community attitudes to the site, with potentially severely damaging results (Fauzen and Bashari 2016). The Wildlife Conservation Society has also worked on the island since 2007, trying to promote sympathetic land use and development by villages surrounding Gunung Sahengbalira (N. Brickle in litt. 2010). A local resident and former bird guide is monitoring the loss of native forest for plantations of exotic tree species and trying to raise awareness of the threat this poses to Coracornis sanghirensis (Sykes 2009; W. Pangimangan in litt. 2015).
17 cm. Medium-sized, drab, thrush-like passerine. Olive-brown above, more chestnut on shoulders and lower back. Paler brownish below, more rufous on belly. Strong black bill and legs. Similar spp. Golden Bulbul Ixos affinis platenae is larger, more olive-green above, yellow on throat and belly. Voice Soft, lisping chweep ...chweep.
Text account compilers
Benstead, P., Bird, J., Brickle, N., Pangimangen, W., Symes, A., Taylor, J., Tobias, J. & Wright, L
BirdLife International (2022) Species factsheet: Coracornis sanghirensis. Downloaded from http://www.birdlife.org on 16/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/08/2022.