Mount Silay and Mount Mandalagan (Northern Negros)

Country/territory: Philippines

IBA criteria met: A1, A2 (2001)
For more information about IBA criteria, please click here

Area: 16,687 ha

Haribon Foundation

Site description (2001 baseline)
North Negros Forest Reserve (NNFR) lies to the north of Mount Canlaon (PH063). It is an old forest reserve, mostly logged except for the two mountains, Mts. Silay and Mandalagan. These have extensive old growth forests on the higher slopes, and are connected by secondary forest. The area of NNFR is 80,454 ha, but only 16,687 ha of forest remains, of which c.75% is old growth and c.25% is secondary. The old growth is mainly above 1,000 m, but is found locally on very precipitous slopes at down to 700 m, and secondary forest is found at down to 400 m. The IBA is defined using the boundary of the remaining forest block, rather than the boundary of NNFR, as much non-forest land is included in that reserve. Much of the forest in this IBA is montane, including mossy forest at the highest altitudes, most of which is primary. There are some areas of primary lowland dipterocarp forest on the lower slopes, and extensive areas of secondary lowland forest. The forest on slopes of Mt Mandalagan is heterogeneous owing to the many steep-sided gorges and ridges in the area, and is very broken. Extensive areas on the steep slopes are, however, not forest, but rather covered by grasses, tree-ferns and scrub. This area is currently the largest tract of old growth forest left on Negros, which has only 4% of its original forest remaining. The secondary forest at 400 m is probably the only ‘true’ lowland forest remaining on Negros (although some forest survives at similar altitude in the Dumaguete City watershed area on Mt Talinis in PH066). This IBA forms the watershed of six major rivers in northern Negros that is the water source of 11 municipalities and cities and irrigates the islands' main rice production areas.

Key biodiversity
There have been several recent studies of the birds of Mt Silay and Mt Mandalagan (notably those of PESCP, the full details of which will be published shortly by Curio et al.), and many of the threatened and restricted-range species of the Negros and Panay Endemic Bird Area have been recorded there or reported by local people. This IBA includes the largest remaining areas of lowland forest on Negros, as well as extensive montane forests, and it is likely to prove to be very important for a number of threatened species, such as Negros-bleeding-heart, Visayan and Writhed-billed Hornbills and Visayan Flowerpecker.

Non-bird biodiversity: The NNFR harbours both endemic plants and animals. For plants these include hardwood tree species (Dipterocarps), palms, orchids, herbs and trees with medicinal value. Animals include Philippine Spotted Deer Cervus alfredi, Visayan Warty Pig Sus cebifrons and butterflies. A giant fruit bat, the critically endangered Negros Naked-backed Fruit Bat Dobsonia chapmani may already be extinct. Several additional endangered mammal species may be present, but no surveys have been conducted yet.

Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Mount Silay and Mount Mandalagan (Northern Negros). Downloaded from on 04/03/2024.