Candaba Swamp
Candaba Swamp is a significant wetland ecosystem located in the provinces of Pampanga and Bulacan in the Philippines, covering over 150 square miles (388 square kilometers). It plays a vital role as a primary nesting and stopover habitat for numerous migratory bird species along the East Asia–Australasian Migratory Flyway. The swamp features a rich diversity of habitats, including freshwater ponds, marshes, and seasonally flooded grasslands, which support a variety of fish species and local agriculture, particularly watermelon and muskmelon farming.
Despite its ecological importance, the swamp faces multiple threats, including illegal hunting, the introduction of exotic fish species, and environmental degradation caused by agricultural practices, pollution, and climate change. Although designated as a bird sanctuary, issues like land development and unsustainable fishing practices continue to impact its biodiversity. The site is crucial for various bird species, including vulnerable and endangered populations, making it a popular destination for birdwatchers and researchers. As efforts to balance human needs and environmental protection evolve, Candaba Swamp remains a focal point for conservation efforts in the region.
Candaba Swamp
- Category: Inland Aquatic Biomes.
- Geographic Location: Asia.
- Summary: A main wetlands site in the Philippines, the Candaba Swamp is a fertile and biodiverse area noted for being a primary nesting habitat for numerous migratory birds.
An ecologically important wetland ecosystem spanning the provinces of Pampanga and Bulacan in the Philippines, Candaba Swamp is known as a primary nesting ground for a host of migratory birds. Spanning more than 150 square miles (388 square kilometers) of arable land, the Candaba Swamp is a rich mosaic of freshwater ponds, swamps, and marshes on a sprawling alluvial floodplain surrounded by seasonally flooded grassland, nipa palm savanna, mangrove forests, and farms known for their production of watermelon and muskmelon. The site of communal fishing grounds that provide critical habitat for fish, including mudfish and catfish, the Candaba also is an ecosystem facing a trio of threats: illegal hunting, the introduction of exotic fish species, and siltation, or the deposition by moving water of fine sand, organic matter, and the like as sediment.
At 36 feet (11 meters) above sea level, Candaba represents one of the lowest points of interior Luzon Island, the largest island of the Philippines archipelago, and acts as a natural flood basin for capturing the wet-season overflow of five small rivers—Maasim, San Miguel, Garlang, Bulu, and Penaranda—that empty into the larger Pampanga River. Just 37 miles (60 kilometers) north of metro Manila, Candaba Swamp is bounded by the towns of San Luis and Arayat in the province of Pampanga; Baliuag, San Ildefonso, and San Miguel in the province of Bulacan; and Cabiao in the province of Nueva Ecija. The swamp is the area closest to the nation's capital that offers very rich biodiversity.
Critical to Bird Species
A main stopover along the East Asia–Australasian Migratory Flyway, which includes Siberia, China, Japan, Hong Kong, South Korea, Singapore, the Philippines, Indonesia, Papua New Guinea, Australia, and New Zealand, Candaba Swamp is filled with a wide array of migratory bird species wintering from October to April. During the dry season of December to May, the swamp itself is mostly dried out. In the January to February timeframe, it is largely drained and converted to melon plantations and rice fields. During this period, large numbers of egrets descend on the swamp's shallow pools to feed on small fish and snails. When the wet season is at its peak, from June to November, the swamp is flooded and used for fish-pond aquaculture.
Located 5 miles (8 kilometers) north of the town of Baliuag, in Bulacan Province, next to the Pampanga River, is a 1-square-mile (3-square-kilometer) shallow water reservoir that is the primary refuge for waterfowl, featuring small islands and floating mats of aquatic plants. Candaba is a critical winter refuge that supports rare migrants such as purple swamp hen (Porphyrio porphyrio), Chinese pond heron (Ardeola bacchus), black-crowned night heron (Nycticorax nycticorax), Von Schrenck's bittern (Ixobrychus eurhythmus), great bittern (Botaurus stellaris), coot (family Rallidae), and Eurasian spoonbill (Platalea leucorodia). Among threatened bird species that have been observed are the spot-billed pelican (Pelecanus philippensis) and the rare streaked reed warbler (Acrocephalus sorghophilus).
The large populations of migratory birds arriving from as far as Australia and Siberia make Candaba a popular bird-watching site for locals, tourists, and scientists. In 1982, approximately 100,000 ducks (family Anatidae) were observed here in one day—a record in the Philippines. Candaba Swamp supports more Anatidae than any other site in the Philippines. The two most abundant species in the swamp are garganey (Anas querquedula) and the Philippine mallard (Anas luzonica), though the latter is listed as a vulnerable species by the International Union for Conservation of Nature (IUCN).
There are significant numbers of other ducks, including the northern pintail (Anas acuta), wandering whistling duck (Dendrocygna arcuata), Eurasian widgeon (Anas penelope), northern shoveler (Anas clypeata), common pochard (Aythya ferina), and mottled duck (Anas fulviga). In the late 1970s, the first observations in the Philippines of gadwall (Anas strepera) and the endangered Baer's pochard (Aythya baeri) were made in Candaba.
Effects of Human Communities
Candaba Swamp is being looked at as a potential source of potable water for the communities of Pampanga, Bulacan, Metro Manila, and neighboring provinces. This decision follows a 2011 water summit that projected a water crisis within fifteen years due to aggressive extraction of the region's groundwater. The creation of a 2,471-acre (1,000-hectare) water reservoir adjacent to the 79,074-acre (32,000-hectare) swamp could also support year-round fishing. Proponents of turning the swamp into a lake say that in addition to solving the flooding problem, it would create a nautical highway connecting the eastern provinces of Nueva Ecija and Bulacan to the western provinces of Pampanga and Bataan.
In recent times, the swamp has been drained earlier in the year—in December or January as opposed to March or April—and has therefore supported fewer wintering birds. More control of water levels to support agriculture will continue to threaten the biodiversity for which Candaba is famous. The Department of Environment and Natural Resources has declared Candaba a bird sanctuary to protect the area, but although there is a permanent ban on hunting, the killing of waterfowl for recreation or food remains a persistent problem.
In the 2020s, the degradation of the wetlands became a serious concern. Land development, garbage dumping, pollution, and overfishing have taken a toll on Candaba. The Society for the Conservation of Philippine Wetlands (SCPW) has shared concerns for the swamp due to the risks posed by unsustainable agriculture and aquaculture practices. Further, much of the swamp is privately owned, which presents a unique problem with conservation since land conversion is within the power of the individual owners, not the government.
Climate change has also affected the area. Farmers note that intense heat often dries the swamp, and heavy rain has caused flash flooding. Experts stress the importance of the wetlands to the migratory birds that nest there, and because they are a large carbon sink that absorbs carbon dioxide, reducing the effects of climate change.
Bibliography
BirdLife International. Philippine Wetlands. BirdLife International, 2011.
Costamero, Jag Lyra. "Land Conversion Threatens Candaba Swamp, Central Luzon's 'Flood Sponge'." Climate Tracker Asia, 27 Nov. 2023, climatetracker.asia/land-conversion-threatens-candaba-swamp-central-luzons-flood-sponge/. Accessed 31 Oct. 2024.
Enano, Jhesset O. "Climate Change Land Conversion Threaten Pampanga Bird Haven." Philippine Daily Inquirer, 3 Feb. 2019, newsinfo.inquirer.net/1080886/climate-change-land-conversion-threaten-pampanga-bird-haven. Accessed 31 Oct. 2024.
Kennedy, Robert S., et al. A Guide to the Birds of the Philippines. Oxford University Press, 2000.
Society for the Conservation of Philippine Wetlands. Conserving Arayat Watershed for the Protection of Candaba Wetlands. PSDN, 2011.
Teves, Catherine. "Candaba Swamp Area Still Likely Submerged This Weekend." Philippine News Agency, 19 Nov. 2020, www.pna.gov.ph/articles/1122314. Accessed 31 Oct. 2024.