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Location Philippines, Region III
Central coordinates 120o 53.00' East  15o 5.00' North
IBA criteria A1, A4i, A4iii
Area 32,000 ha
Altitude 11 m
Year of IBA assessment 2001

Haribon Foundation

Site description Candaba Swamp is near the towns of Candaba, San Miguel and San Ildefonso, c.50 km north-north-west of Metro Manila, in Pampanga and Bulacan Provinces, central Luzon. It is a complex of freshwater ponds, swamps and marshes with surrounding areas of seasonally flooded grassland, arable land and palm savanna on a vast alluvial flood plain. The entire area is usually flooded in the wet season, but most of it dries out during the dry season (late November to April) and is converted into rice fields and plantations of watermelons. The main area for waterfowl is an impoundment of about 300 ha, with a mixture of open shallow water, small islands, and rafts of floating vegetation, adjacent to the Pampanga River about nine kilometers north of Baliuag. However, this area is now drained earlier in the year than in the past, and it no longer attracts many waterfowl. The isolated Mt Arayat, which rises to 1,023 m and has disturbed lowland forest on its slopes, is adjacent to Candaba Marsh but is not included in the IBA. Most of the flood plain has been converted to privately owned agricultural and residential land except for the core area of approximately 500 ha. The impoundment is used as a fishpond during the rainy season, and then drained in January or February to be used for agriculture. Candaba Swamp acts as a natural flood retention basin holding wet season overflow from the Maasim, San Miguel, Garlang, Bulu and Penaranda Rivers, and draining into the Pampanga River. The swamp was a traditional waterfowl hunting area in the past, and some hunting of ducks and rails, although now illegal, still occurs. It is also a favourite spot for local and visiting bird watchers and naturalists, and possibly has some potential for nature oriented outdoor recreation and conservation education as there are few other places so close to the metropolitan area of Manila that support as much wildlife.

Key Biodiversity Candaba Swamp was formerly an extremely important staging and wintering area for ducks, especially in October and November when the swamp regularly supported between 5,000 and 10,000 birds. In 1982, about 100,000 ducks were observed in a single day. No other site in the Philippines has been known to support such large concentrations of Anatidae, but the number of wintering wildfowl has recently declined dramatically. Several threatened waterbirds occurred there in the past, although the populations of some of these have presumably declined or disappeared. However, it still supports the only known regular wintering population of Streaked Reed-warbler in the world. Some of the restricted-range birds of the Luzon EBA were recorded adjacent to this IBA on Mt Arayat in the late 19th century, including Green Racquet-tail Prioniturus luconensis (threatened), Red-crested Malkoha Phaenicophaeus superciliosus, Rufous Coucal Centropus unirufus, Grey-backed Tailorbird Orthotomus derbianus and White-fronted Tit Parus semilarvatus. This small mountain is reported to retain some forest cover, but there appears to be no recent information on the status of these species there. There has been no mammal survey in Candaba swamp and on Mt Arayat.

Non-bird biodiversity: There has been no mammal survey in Candaba swamp and on Mt Arayat.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Northern Pintail Anas acuta winter  2001  present  A4i  Least Concern 
Philippine Duck Anas luzonica resident  2001  present  A1, A4i  Vulnerable 
Garganey Spatula querquedula winter  2001  present  A4i  Least Concern 
Great White Egret Ardea alba unknown  2001  present  A4i  Least Concern 
Spot-billed Pelican Pelecanus philippensis non-breeding  2001  present  A1  Near Threatened 
Streaked Reed-warbler Acrocephalus sorghophilus winter  2001  present  A1  Endangered 
A4iii Species group - waterbirds unknown  2001  20,000 individuals  unknown  A4iii   

IBA Monitoring

2015 very high very unfavourable negligible
Medium - based upon reliable but incomplete / partially representative data

Agriculture and aquaculture annual & perennial non-timber crops - agro-industry farming happening now majority/most of area/population (50-90%) very rapid to severe deterioration very high
Biological resource use hunting & collecting terrestrial animals - intentional use (species being assessed is the target) happening now whole area/population (>90%) moderate to rapid deterioration very high
Human intrusions and disturbance work and other activities happening now small area/few individuals (<10%) moderate to rapid deterioration low
Natural system modifications dams & water management/use - abstraction of surface water (agricultural use) happening now majority/most of area/population (50-90%) moderate to rapid deterioration high

Wetlands (inland)   32000 37 1 poor (40-69%) very unfavourable

Little/none of site covered (<10%)  No management planning has taken place  Very little or no conservation action taking place  negligible 


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

Protection status This is a potential Ramsar site but not a protected area.

References References: Alonzo-Pasicolan (1990); Custodio (1996); Davies et al. (1990); Lambert (1993); Scott (1989).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Candaba swamp. Downloaded from on 26/10/2016

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