The number of species and the populations of waterbirds in Muara Angke natural conservation area, North Jakarta, have decreased because of water pollution and human encroachment into the area, an environmental organization says.
During its annual survey on Saturday, volunteers of Jakarta Green Monster (JGM) found 206 waterbirds, down from 333 last year, with only 18 species identified, down from last year’s 23.
JGM reported that the missing species were the Little Cormorant (Phalacrocorax sulcirostris), Great-billed Heron (Ardea sumatrana), White-browed Crake (Porzanna cinerea), Purple Swamphen (Porphyrio porphyrio) and Black-naped Tern (Sterna sumatrana).
However, a very rare species, the Oriental Darter (Anhinga melanogaster) and two endangered non waterbird species, Sunda Coucal (Centropus nigrorufus) and Black-winged Starling (Acridotheres melanopterus), were spotted on Saturday.
JGM has been studying the Waterbirds in the area each year since 2006, in recognition of World Wetland Day on Feb. 2, which marks the anniversary of the signing of the Convention on Wetlands of International Importance in 1971.
JGM volunteer Ady Kristianto said water pollution and human encroachment were the main causes of the decline in bird numbers. The darkened water in the area had been heavily polluted because of an accumulation of plastics and styrofoam from the Angke River, he said.
Liquid waste from nearby housing complexes and makeshift houses was also dumped there.
“Water pollution has slowed the growth of mangrove trees, which provide shelter to the birds, and has also caused a decline of fish stocks, the main food source for waterbirds. Some species are unable to adapt and had flown away to less polluted areas,” he said.
Human encroachment had disrupted the habitat, Ady said.