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Site description (2001 baseline):
Site location and context
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.
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.
Pressure/threats to key biodiversity
The major pressure on this IBA is from an influx of migrants and illegal settlers into the watershed, who have engaged in kaingin, land conversion for agriculture and the illegal collection of timber. This is occurring mainly along the eastern and southern perimeters of the watershed, where it is believed that the forests are particularly vulnerable because there is no buffer of brush or open-canopy forest between the old growth forest and occupied lands.
To the north of Pasonanca Watershed are open canopy residual forests that fall within the Curuan Watershed. This area is subject to intensive illegal logging and the timber is processed by several mini-sawmills within the forest zone. On the eastern portion, the rough terrain and high elevations have been a deterrent to settlers. However, there already are several new clearings in this area. If protection is not increased in this section, heavier incursion into the Curuan Watershed is certain in the near future.
Conservation responses/actions for key biodiversity
The DENR and Water District have deployed forest guards and watershed officers to protect the area, and try to prevent the illegal collection of timber and wildlife hunting which have been reported from within the watershed. This has minimized but not completely eradicated these illegal activities.
A reforestation project of the Zamboanga City Water District (ZCWD) covers 300 ha while that of the CENRO of Zamboanga City covers 75 ha. These are planted with exotic species, particularly gmelina Gmelina arborea, bagras Eucalyptus sp. and mahogany Swietenia mahogany, which are unfortunately of limited value to the native wildlife.
The DENR Region 9 has completed a PASA of the area and has submitted a report that recommends the establishment of Pasonanca Watershed as a Natural Park under the NIPAS. An Initial Protected Area Plan (IPAP) has also been drawn up as a requirement for recommendation as a NIPAS site. The campaign for approval to the NIPAS started in November 1997.
Pasonanca Watershed is a research area of the Western Mindanao State University in Zamboanga City.
PAWB installed the DENR Biodiversity Monitoring System in this IBA in mid 2000.
Pasonanca Watershed Forest Reservation was declared by Presidential Proclamation No. 199 on 17 December 1987. The protected area covers 12,106.61 ha with a buffer zone of 5,307 ha.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Pasonanca watershed (Philippines). Downloaded from
https://datazone.birdlife.org/site/factsheet/pasonanca-watershed-iba-philippines on 22/11/2024.
