Mandai mangroves and mudflats
Significance of Singapore's Mandai Mangroves
in response to a query by Samantha Sng for the series Nature at Your Doorstep

By N. Sivasothi, 31st July 2003

In 1990, the year Sungei Buloh was officially gazetted, D. H. Murphy and J, B. Sigurdsson of NUS' Department of Zoology submitted a paper to the Sungei Buloh Development Committee of the Ministry of National Development. There, they argued the case for a wider extension of conservation along the coast of the western Johor straits and a broader scope for conservation activities.

They pointed out that 'while Sungei Buloh is relatively isolated and a major bird roost, Mandai does not provide the conditions required for roosting waders but the mudflats next to the Mandai mangroves are a major feeding area for the birds that roost at Sungei Buloh.' The further attraction of Mandai was that 'if sufficient mangrove was protected, it could be self sustaining!'

In 1995, Master's student Ms Christine Tan submitted a thesis under the supervision of Dr Jon Baldur Sigurdsson of the Department of Biological Sciences, National University of Singapore. The thesis addressed the feeding ecology of overwintering waders on Singapore intertidal mudflats.

There is an annual migration of some 12 - 15 thousand million birds from the northern Eurasian continent to Africa and southern parts of Asia on an annual migration in search of overwintering areas. This annual migration occurs along traditional routes known as flyways. The route along Singapore is called the East Asian Australasian Flyway.

Thousands of waders, e.g. Sandpipers and plovers arrive in their thousands every year to Singapore. Some stop over for a short while on their way further south to places like Australia, while others stay here during the northern winter. An important feeding area to all these birds are the intertidal mudflats.

The Sungei Buloh Wetlands Reserve was set up as a sanctuary for migrating waders and has been a focal point for Singapore for migrating waders. Visitors are able to view waders particularly during high tide when former prawn ponds are maintained at low tide to enable continued feeding by the waders and a closer view by visitors.

However, protecting Sungei Buloh is not enough in the long term. The Kranji-Mandai mudflats provided the food source that supported the waders using the Sungei Buloh Wetlands Reserve as a high tide roosting area. The favourable status of these areas is due in part to ecological features. The study pointed out soil characteristics that supported a higher density of prey in comparison to some feeding sites in other countries along the migration route.

An earlier paper pointed out that 'the high organic production of the mangroves is in part exported to the mudflats contributing to the high production of invertebrate fauna such as worms, molluscs, crustacea and small fish on which the shorebirds feed. It is therefore no accident that the preferred feeding areas are the most extensive mudflats adjacent to the largest block of mangroves.'

Singapore mudflats also shared a marked absence of competitors or predatory threats to waders. Additionally they have been extremely favourable to such wildlife due to their isolation from the city area and the relative lack of human disturbance. 'Certainly Mandai's relative inaccessibility reduces the number of sports fishermen and shellfish pickers than are common in other areas, which are heavily used by such people, especially at weekends.'

Setting aside Sungei Buloh in the first place in 1994 and its subsequent historic elevation to reserve status in December 2001 was a laudable step by Singapore's government. In December 2002, Sungei Buloh Wetland Reserve received accolades when it was the first Southeast Asian site to be inducted into the East Asian Australasian Shorebird Site Network by Wetlands International.

But the protection of migratory bird populations require a holistic approach to land use policies bordering the Johor Straits. As it is throughout the East Asian Australasian Flyway, the greatest and most immediate threat to the migrating waders that we see in Sungei Buloh is the destruction of the feeding habitats by reclamation or other development. E.g. localised impact has already occurred in parts such as the work upstream of the Mandai rivers.

In March 2003, the Ramsar Bureau announced that Malaysia had designated three new areas Wetlands of International Importance. These areas, Pulau Kukup, Sungai Pulai and Tanjung Piai, are all located in south-western Johor. This moves will contribute to continued existence of the East Asia Australasian Flyway.

The possible loss of the size and quality of the feeding grounds at Mandai mudflats are a threat to the spectacular international migrant wader population that we have been lucky to enjoy so far at Sungei Buloh Wetlands Reserve. This is certainly food for thought as we approach the 10th Anniversary of the Sungei Buloh Wetlands Reserve.

D. H. Murphy & J. B. Sigurdsson, 1990. Birds, mangroves and man: prospects and promise of the new Sungei Buloh Bird Reserve. In L. M. Chou & P. K. L. Ng (eds), Essays in Zoology. Department of Zoology, National University of Singapore. Pp. 233-243.

Tan, C. P. Y., 1995. The feeding ecology of migratory waders, pacific golden plovers (Pluvialis fulva) and whimbrels (Numenius phaeopus variegatus) on some intertidal flats in Singapore. Unpublished M. Sc. thesis (Supervisor : Dr. J.B. Sigurdsson) submitted to the Department of Zoology, Faculty of Science, National University of Singapore, 1996. Xi + 127 pp.

Mah, B. T., 2001. Speech by Mr Mah Bow Tan, Minister for National Development at the launch of the upgraded facilities at Sungei Buloh Nature Park on 10 November 2001, 9.30am at Sungei Buloh Nature Park. MND Webpage.

Neo, H. M., 2002. "Sungei Buloh on world map as important bird site". The Straits Times, 8th December 2003.

Liazzat Rabbiosi, 2003. "Malaysia names three new Ramsar sites in Johor State." Based on Ramsar Information Sheets, 11th June 2003.