Pasonanca Watershed is only 7 km north of Zamboanga City at the tip of the Zamboanga Peninsula in southwestern Mindanao. It has the largest block of old growth lowland dipterocarp forest remaining in Region 9, and a DENR Protected Area Survey Assessment (PASA) reports that old growth and secondary growth forest covers about 60% of the area. The rest is agricultural land, coconut plantations and built-up areas. Rock formations and numerous rivers and springs provide additional habitats for wildlife. It has a rolling terrain with moderate to steep slopes. Tenured migrants have occupied part of the watershed since the 1950s. Since it is close to the city, housing projects have been constructed by developers at the edge of the watershed. There is also a picnic and camping area adjacent to the watershed, including a Boy Scouts of the Philippines camp. Pasonanca Watershed is the only source of potable water for Zamboanga City, and the Tumaga River also provides industrial and irrigation water for the area around the city.
Many of the threatened and restricted-range species of the Mindanao and Eastern Visayas Endemic Bird Area have been recorded in or near to Pasonanca Watershed, including recent records of the threatened Mindanao Bleeding-heart, Philippine Kingfisher, Philippine Leafbird and Little Slaty Flycatcher, and Zamboanga Bulbul, which is confined to western Mindanao and Basilan. It is likely that the good quality habitat there supports some important populations of these birds.
BirdLife International (2019) Important Bird Areas factsheet: Pasonanca Natural Park. Downloaded from http://www.birdlife.org on 18/11/2019.