Justification of Red List Category
This species is listed as Vulnerable because it is undergoing a rapid and continuing population decline as a result of extensive forest loss at low to mid-altitudes within its range.
Formerly widespread on Negros, it is now restricted to seven known localities, although it is still locally common. It appears much scarcer on Panay, where there are recent records from just three localities in the west. It is presumed extinct on Guimaras, where it has not been recorded for over a century. In total the population is estimated to number 10,000-19,999 individuals, equivalent to 6,667-13,333 mature individuals, rounded here to 6,000-15,000 mature individuals.
This lower and mid-altitude forest species occurs at lower densities in secondary forest than it does in primary forest. Total forest loss has been rapid on Panay and Negros and hence it must have declined rapidly. The extent of forest habitats had been drastically reduced by 1988 so it is unlikely that the species continues to decline at the same rapid rate, simply because there is little forest left to remove.
Coracina ostenta is endemic to the Western Visayas in the Philippines, where it is known from Panay, Negros and Guimaras (Collar et al. 1999). Formerly widespread on Negros, it is now restricted to seven known localities, although it is still locally common. It appears much scarcer on Panay, where there are recent records from just three localities in the west. It is presumed extinct on Guimaras, where it has not been recorded for over a century. Given that Panay and Negros are largely deforested in the lowlands, it is inferred that it occupies a small, fragmented range.
It inhabits lowland and mid-montane forest, usually below 1,100 m, but very occasionally up to 2,150 m. It also occurs at lower densities in secondary forest. It frequents the upper storey of large trees. Significant populations are unlikely to persist in montane forest.
Chronic deforestation led to its presumed extinction on Guimaras. Habitat degradation, particularly selective logging of large trees, continues to pose a serious threat to remaining fragments throughout its limited range. The main drivers behind deforestation have been agricultural conversion, wood pulp plantations, oil-palm plantations, commercial logging and urban encroachment.
Conservation Actions Underway
It occurs in Mt Canlaon Natural Park (Negros) and the North Negros Forest Reserve, which only receives nominal protection. It also occurs in the proposed Central Panay Mountains National Park, which reportedly contains the largest block of remaining forest in the Western Visayas, and Mt Talinis/Twin Lakes (Negros), which both benefit from conservation funding.
25 cm. Canopy-dwelling, black-and-white passerine. Male has black head and upper breast, forming dark hood. Dark grey back and rump, black wings with white wing-patch across greater coverts and tertials. Black tail with white tips to outer tail feathers. Dark grey breast and belly, white undertail-coverts. Dark bill, iris and legs. Female similar to male although head grey (lacks black hood) and underparts paler. Similar spp. Bar-bellied Cuckoo-shrike C. striata larger and lacks white in wing. Voice Loud, sharp whistles tseeuu, sometimes running together to form jangled phrase. Hints Joins mixed feeding flocks. Tends to stay in the canopy.
Text account compilers
Benstead, P., Bird, J., Davidson, P., Lowen, J., Peet, N., Pilgrim, J., Taylor, J.
BirdLife International (2020) Species factsheet: Edolisoma ostentum. Downloaded from http://www.birdlife.org on 31/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/10/2020.