Most of the remaining closed-canopy forests in Region III are found in Bulacan Province, principally in the Angat Dam Watershed which lies about 35 km to the north of Metro Manila. The watershed supports lowland dipterocarp stands on moderate to very rough terrain between elevations of 490 to 920 m, although much of the accessible forest is now degraded, and there are many areas of secondary bamboo. The forests here are of relatively low stature, and grow on what appear to be poor soils with no humus layer. The areas surrounding the forest are covered in sparse scrub and grassland. The forests here are essential for the water and the electricity supply of Manila, much of which is generated by the Angat Hydroelectric Dam.
The forests around Angat Dam are a popular destination for bird-watchers, and there are recent records of many of the threatened and restricted-range birds of the Luzon Endemic Bird Area. This is one of the few places where there are recent records of large flocks of Spotted Imperial-pigeon. Some of these species have also been recorded just outside the IBA at Ipo Dam, and the record of the extremely poorly known Worcester's Buttonquail there is of particular interest.
Non-bird biodiversity: Mammals recorded in the area include two globally near-threatened species, Crab-Eating Macaque Macaca fascicularis and Philippine Warty Pig Sus philippensis, and the Data Deficient Philippine Brown Deer Cervus mariannus.
BirdLife International (2021) Important Bird Areas factsheet: Angat watershed. Downloaded from http://www.birdlife.org on 02/08/2021.