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Importance of Kranji Marshland for Nature
Apart from the birdlife, it must be said that very little is known of the biodiversity of the Kranji Reservoir environs. The Kranji Reservoir environs, with its variety of land cover and habitats, harbour an abundant birdlife that is rich in species.

A total of 140 species has been recorded by the Nature Society (Singapore) since 1985, about 40 per cent of the total (350) recorded for Singapore, which is very impressive (H. C. Ho, latest compilation). Out of this total, 82 are considered resident species, while the rest are either winter visitor or passage migrant or non-breeding visitor. Wetland species (inclusive of specialists and non-specialists) amount to 47, out of which 25 are resident, revealing that a large variety of birds are dependent in some way or other on the Reservoir freshwater marshes.  

The Baya Weaver feeds almost exclusively on grass seeds.
This species prefers to build
its pendulous nest over water.

The Reservoir marshes are the stronghold of the Grey Heron (Ardea cinerea) and Purple Heron (Ardea purpurea). The Grey Heron is a Nationally Threatened Species, while the Purple Heron is a Nationally Near-threatened Species (Lim, 1999). The Grey Heron is omnivorous and tends to be gregarious. They are concentrated in large numbers at the lower part of the Kranji Reservoir - especially at the mudflat to the east of the Kranji Bund and the bay at the edge of the Kranji Radio Transmitting Station. A survey in 2000 revealed that out of 66 Greys recorded, 56 (85 per cent) are found in the Lower Kranji Reservoir area (Ho, 2000). Observations have shown that the nesting Greys at the Sungei Buloh Nature Reserve, about 2 km away to the north, resort to the reservoir for food to feed their nestlings. Currently, there is no known existing Grey heronry in the marshes. In the past, the largest known Grey heronry in Singapore with about 60 nests was located in a remnant mangrove patch in the South Kranji Bund Marsh (Wells, 1999). This patch, together with the heronry, has been overwhelmed by development.

The Purple Heron is just as conspicuous as the Grey but they do not usually congregate in groups when feeding. The species is also omnivorous, but fish predominates, accounting for more than 50 per cent of its diet (Hancock & Elliott, 1978). Unlike the Grey, they prefer feeding grounds that are grassier and less muddy. The Survey in 2000 shows that out of 49 Purple recorded, 33 (67 per cent) are found in the upper reservoir areas (Ho, 2000). Most of those in the Kranji Bund area are actually seen at the edge or within the marshes.

Also, unlike the Grey, the Purple has a preference for nesting in ground ferns or tall grasses (Hancock & Elliott, 1978), although trees are not excluded as in the mixed heronry with the Grey at Sungei Buloh. There is a record in 1983 of 20-30 pairs nesting in the Acrostichum ferns of the Reservoir marshes (Wells, 1999), but it is now uncertain whether nesting in the ferns or any other parts of the Reservoir still goes on. Like the Grey, observation has shown that the nesting parents as well as immatures from the Buloh heronry resort to the Reservoir marshes for food.

The Bitterns are another group within the heron family (Ardeidae) that is specially adapted to the freshwater wetland. Generally skulking birds, they prefer to haunt the long grasses of the marshes. At least four species are found, of which the Cinnamon Bittern (Ixobrychus cinnamomeus) and the Yellow Bittern (Ixobrychus sinensis) are resident. The Yellow and the Cinnamon abound here, with their numbers augmented in the migratory season by winter visitors. Both these species generally nest in grassy or reedy situations and feed on fish, amphibians and invertebrates (Wells, 1999). The Reservoir Marshes probably hold the largest concentration of the Cinnamon in Singapore (Scott, 1989).  

The Yellow Bittern makes its home among aquatic vegetation

Rails are typical freshwater marshland birds. Eight species are found in the Reservoir marshes. The most conspicuous in terms of its size and colour is the Purple Swamphen (Porphyrio porphyrio). An uncommon resident species, the Swamphen is also a Nationally Near-threatened Species (Lim, 1999). It breeds only in two areas of Singapore - in the Kranji Reservoir and the Western Catchment (Lim, 1992). It is usually seen foraging for plant and other food by the edge of the Kranji Bund Marshes. The most commonly seen rail is the pretty White-breasted Waterhen (Amaurornis phoenicurus), thriving wherever there is a pond, river, stream or an old monsoon drain. Seven other species of rails are also found here, such as the Slaty-breasted Rail (Gallirallus striatus), White-browed Crake (Porzana cinerea) and Ruddy-breasted Crake (Porzana fusca).

Another group of birds that is also specially adapted to the marshland habitat is the reed-warblers. Four species, all winter visitor/passage migrant, are found in the Reservoir marshes. Nervous and shy birds, they are not easily seen by casual observers. The most common is the Oriental Reed-warbler (Acrocephalus orientalis), whose presence in the tall grasses is usually announced by its shrill, agitated cries.
Other common species of the Reservoir marshes are the Yellow-bellied Prinia (Prinia flaviventris) and the Zitting Cisticola (Cisticola juncidis), both residents. They, are also shy species, the latter usually seen when flushed while the former is more often heard than seen, its trilling songs being a typical feature of the freshwater marshes. There are also many species that use the marshes as foraging and hunting grounds, such as Lesser Coucal (Centropus bengalensis), Black-winged Kite (Elanus caeruleus), Baya Weaver (Ploceus philippinus), and the Munias (Lonchura spp.) but which are also at home on dry grassland or scrubland.  

A beautiful raptor,
the Black-winged Kite,
can be seen soaring
over scrubland

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