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Location Philippines, Region XIII
Central coordinates 125o 57.00' East  8o 9.00' North
IBA criteria A1, A2, A4i
Area 19,197 ha
Altitude 40 - 50m
Year of IBA assessment 2001

Haribon Foundation

Site description Agusan Marsh is near Bunawan in the interior of north-eastern Mindanao Island, Agusan del Sur Province. It is a vast complex of freshwater marshes and watercourses with numerous small shallow lakes and ponds in the upper basin of the Agusan River and its tributaries. The rivers rise in the hills of eastern Mindanao and cause extensive flooding in the marshes from November to March. The main habitats of the marsh include freshwater swamp forest (c.49%), secondary scrub (c.14%), herbaceous swamp (c.7%), freshwater lakes, pools and rivers (c.10%), rice paddies and other agricultural land (c.6%) and small settlements (c.6%). Some parts of the marsh have been converted into fishponds. The main economic activities in the marsh are fishing, aquaculture and agriculture (mainly rice and cash crops), but the region is sparsely populated because of the annual flooding of the Agusan River. The marsh is an important source of water for irrigation. It has an important hydrological function, holding excess water at times of high flow, and ensuring adequate flow during dry periods. If the marsh were to be drained, the communities downstream would be prone to serious floods and droughts.

Key Biodiversity This IBA is important for a variety of waterbirds, notably herons and egrets. Several threatened species have been recorded in or near to Agusan Marsh in the past, mainly forest birds, but it is unclear whether they have significant populations in the remaining forests there. However, Silvery Kingfisher has recently been recorded in the marsh itself, and there may be a significant population of Philippine Duck there.

Non-bird biodiversity: The marshes support the largest population of the Estuarine Crocodile Crocodylus porosus remaining in the Philippines, and it has been suggested that the endangered Philippine Crocodile C. mindorensis may also be present

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Philippine Duck Anas luzonica resident  2001  present  A1, A4i  Vulnerable 
Purple Heron Ardea purpurea unknown  2001  present  A4i  Least Concern 
Nisaetus philippensis resident  2001  present  A1  Not Recognised 
Sarus Crane Antigone antigone breeding  2001  present  A1  Vulnerable 
Spotted Imperial-pigeon Ducula carola resident  2001  present  A1  Vulnerable 
Alcedo argentata resident  2001  present  A1  Not Recognised 
Rufous-lored Kingfisher Todiramphus winchelli resident  2001  present  A1  Vulnerable 
Celestial Monarch Hypothymis coelestis resident  2001  present  A1  Vulnerable 

IBA Monitoring

2001 high not assessed not assessed
Good - based on reliable and complete / representative data

Agriculture and aquaculture annual & perennial non-timber crops - small-holder farming happening now some of area/population (10-49%) slow but significant deterioration medium
Agriculture and aquaculture marine and freshwater aquaculture - subsistence/artisinal aquaculture happening now some of area/population (10-49%) slow but significant deterioration medium
Biological resource use gathering terrestrial plants - unintentional effects (species being assessed is not the target) happening now some of area/population (10-49%) slow but significant deterioration medium
Biological resource use hunting & collecting terrestrial animals - intentional use (species being assessed is the target) happening now majority/most of area/population (50-90%) slow but significant deterioration high
Biological resource use logging & wood harvesting - unintentional effects: large scale happening now some of area/population (10-49%) moderate to rapid deterioration high
Natural system modifications dams & water management/use - large dams likely in long term (beyond 4 years) some of area/population (10-49%) no or imperceptible deterioration low
Pollution industrial & military effluents - seepage from mining happening now small area/few individuals (<10%) slow but significant deterioration low

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Agusan Marsh Wilderness Sanctuary 42,009 protected area contains site 19,197  
Agusan Marsh Wildlife Sanctuary Wetlands of International Importance (Ramsar) 14,836 unknown 0  


IUCN habitat Habitat detail Extent (% of site)
Forest   -
Wetlands (inland)   -
Artificial - terrestrial   -

Protection status Agusan Marsh Wildlife Sanctuary was declared by Presidential Proclamation 913 in 31 October 1996. The area was given Ramsar site status in 1999. It is a GEF CPPAP site (including Esperanza).

References Davies et al. (1990); Scott (1989).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Agusan Marsh. Downloaded from on 25/10/2016

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