Horseshoe crabs at Sungei Buloh Nature Park

wetlands
a publication of Sungei Buloh Nature Park

Vol 8 No 2
Aug 2001

survivors of time: the horseshoe crab

insect study
tips on insect watching

zonation:
the landward mangrove fringe

landmark invasion
a walk in the past

fat worries of common
redshanks

Allan Teo
long-lasting companion
of the park

young naturalists
of the park

a nature journal
javan munia

survivors
of time

linda goh
senior education officer
presents some interesting facts about these old timers

Their ancestors were present to witness the rise and fall of the Dinosaurs. As dinosaurs struggled to survive, these creatures managed to outlast them for millions of years with apparently little change. In our present age, these living "fossils" which cross two boundaries, namely the sea and land's edge are called the Horseshoe Crabs.

what crab! no crab! The name Horseshoe was derived from the U shape of the shell that resembles the hoof of a horse. However, Horseshoe Crabs are not crabs. They are more closely related to spiders and scorpions.

survival series To date only 4 species of Horseshoe Crab have survived, ff which 3 species can be found in the Southeast Asian region. The tough mantle of the Horseshoe Crab prevents any potential predators from accessing the soft-bellied underparts. They have no known natural enemies except perhaps Man. Their capacity to endure extreme temperatures and salinity is believed to help to ensure the survival of these species. Slow and steady, they are indeed the real survivors of time.

mudflat cuisine Horseshoe Crabs are scavengers and feed on whatever they meet on the mudflats. They do not have jaws and have to depend on the stiff hairs on the base of their legs to grind food. In other words, they have to walk in order to chew!

growing years Growing is by means of moulting. After each moult, they emerge 25% larger than the last. It takes about 16 moults before they attain adulthood. They are sexually mature individuals at the age of 9 to 11 years. These creatures can live up to 19 years.

body parts The menacing looking tall gives the illusion that it is used as a weapon. However, the telson or tail acts as a rudder to steer the Horseshoe Crab through the sand and to right itself when it accidentally tips over.

battle of the sexes Males hitch-hiking on the females can be observed during the mating season. The males, which are much smaller, cling on to the females for long periods of time before the eggs are laid in dug out nests. That is why some locals identify the Horseshoe Crabs with matrimonial fidelity.

eye-deal Horseshoe Crabs have been used for eye research as their large eyes and large optic nerve are easy to study. A great deal of what we know of the human eye and how we see are attributed to research done on their eyes.

royal blood Two biologists from NUS had a breakthrough when they discovered an enzyme known as Factor C that is extracted from the Horseshoe Crab's blood. This enzyme has shown to be more powerful and efficient in killing bacteria then the common antibotics. 4 US patents have been obtained for the replicated gene.

The Horseshoe Crabs have successfully survived for millions of years. Their future depends on how much people understand and appreciate their importance to other wildlife and Man as well as the conservation practices taken to conserve them.

Help Sungei Buloh Nature Park to protect these animals by taking care of their habitat!

© Sungei Buloh Nature Park

insect study

by choo-toh get ten
senior education officer

Insects are the most abundant and diverse group of animals on earth.

shield bug

Over a million species are described, and millions more exist. They are remarkably adapted to living everywhere on land, in the air and in fresh water. In the Asian mangroves, insects markedly dominate all life forms.

Leaving the Visitor Centre, first time insect scouts may be disappointed at the apparent scarcity of other insects.

grasshopper

The truth is, these tricky little creatures can hide or camouflage themselves very well amongst the vegetation.

If you could stop walking for a while to look closely at the surrounding vegetation, you will soon see insects crawling on leaves or flying about. just be patient and observant, know when, where and how to zoom in on their likely hideouts, and the amazing, bizarre world of insects will be unveiled before you.

At Sungei Buloh Nature Park, visitors are otten greeted by the more flamboyant of these six-legged arthropods.

Amidst the incessant chorusing of the cicadas, the colourful buttertflies flutter around the butterfly trail, the solitary bumble bee buzzes amongst flowers, and the dragonflies glide swiftly or hover over the lotus pond.

animal taxa

Protoza	18
Sponges-Bryozoa	5
Coelenterata-Ctenophora	3
Non-polychaete worms	13
Polychaetes	11
Crustaceans	229
Insects-Arachnids	500
Molluscs	211
Echinodermata	1
Fish	283
Reptiles	22
Amphibians	2
Birds	177
Mammals	36

Number of animal species recorded
in Asian Mangroves (Modified from IUCL 1983)

tricky little creatures

where to find insects
on plants
The actively growing, more nutritious or palatable parts of plants, e.g., shoots, buds, young/semi mature leaves, flowers, fruits, seeds, veins on underside of leaves.

Around their homes, e.g., ant nest, termite mounds or tracks, cases of bagworms.

Where damage or abnormalities occur, e.g., leaves distorted, rolled, webbed or folded, holes, cuts, burrows, stunting, wilt, colour change, black sooty mould.

Near traces of insects, e.g., cast skin, faeces, waxy or sugary secretions, silky web, egg or pupal cases.

in other habitats
In fresh or brackish water, under leaf litter, rocks, fallen logs, in/on mud or soil.

when to find insects
Generally throughout the year, but some are abundant only when food supply and environment favour their multiplication.

For day-active insects, e.g., pollinators and many leaf feeders, at most times of the day, especially late morning and late afternoon.

For nocturnal insects, e.g., moths, cockchafers and other beetles, mostly at dusk or just after sunset.

Do not look for insects right after rain when foliage is still wet.

how to get close
to watch and study insects
Wear clothes of neutral colors or shades of green, not gaudy colours, or black unless you like mosquitoes.

Bring a 10x hand lens, or 8-20x eye lens for examining small insects, or binoculars for examining those perched high up or far away.

Bring along a camera with tele-macro lens for photographic record.

Approach active, flying insects quietly and slowly, minimizing body movements and air vibration. Avoid casting shadows over them and remember to keep clear of insects which sting.

If necessary, carefully capture active flying insects in a clear container for closer examination before releasing them back to where they are found.

what to observe
Having found insects, never miss the chance of observing their social behaviour, hunting techniques, feeding habits, home building activities, and last but not least, the myriad of their colours and structures that enable them to escape or survive the attack of their natural enemies.

reference guide
Parker, S.1992. Insects. Dorling Kindersley Limited.
Preston-Mafham, R and K, Preston-Mafham. 1996. The Natural History of Insects. The Crowood Press.
Sterry, P. 1997. Insects - A Portrait ot The Animal World. Todtri Productions Limited.
Stokes, D. W. 1983. Stokes Guide to Observing Insects. Little Brown and Company.

© Sungei Buloh Nature Park

zonation
& the landward mangrove fringe

ali ibrahim
conservation officer
highlights some interesting back-mangrove trees found in Sungei Buloh Nature Park

Generally, the seaward edge of the mangrove is dominated by pioneer species of Avicennia and Sonneratia.

On the bank of river estuaries, Rhizophora replaces their position. Behind this is a zone of mixed mangrove forest species of Rhizophora, Sonneratia, Bruguiera, Ceriops, Kandelia, Xylocarpus, Lumnitzera and Excoecaria.

But along rivers or in estuaries, groves of Nipah palms are usually found.

Moving towards the landward side of the mangrove forest, at the upper limit of salt-water penetration, where soil is of firm clay, various tree species represented here can adapt and grow within their respective range of tolerance to the influence of salt or brackish water. This is also the zone flooded by exceptional high water spring tides.

their presence ...
Mangroves that are badly disturbed or found on narrow coasts do not show well defined series of zones paralleling the coast. The phenomenon of zonation is still not fully understood. Factors controlling zonation lie in the response of tree species to salinity, tidal influence and soil conditions. The morphology, buoyancy and mode of establishment of propagules and its competition among the species are other possible factors affecting zonation.

The landward mangrove fringe communities share and compete for the same pollinators with the true mangrove communities as well as share the same predators and parasites. In the latter instance, they perhaps benefit the mangroves by playing as alternative hosts. Their presence also exemplifies the adaptive and evolutionary transition of land plants and may give valuable clues as to how mangroves were derived.

Examples of some of the interesting trees found in Sungei Buloh Nature Park back-mangrove community ...

Jati laut Podocarpus polystachyus is the only gymnosperm found in the swamp. Its long narrow leaf blade has an interesting light green flush when juvenile.

Putat ayam Barringtonia racemosa
has leaves obovate-lanceolate with leaf margin toothed and flowers on pendulous spikes.

Dungun Heritiera littoratis has leaves with silvery-white undersurface and keeled, boat-shaped, brown fruits.

Tui Dolichandrone spathacea is an endangered species, with pinnate leaves, very long tubular white flowers and long seed pods containing corky, winged seeds.

Portia tree Thespesia populnea has hibiscus-like yellow flowers which turn purple and fruits that are water-borne.

Pong pong tree Cerbeia odollam may remind you of a frangipani tree with white, yellow-eyed flowers and green turning red, apple-like fruits.

Katong laut Cynometra ramiflora has one to two pairs of leaflets and wrinkled and knobbed fruits.

Ipil Intsia bijuga is a tall tree with spreading crown and flat oblong seed pods.

Barat-barat Cassine viburnifolia is a small tree with inconspicuous greenish white flowers and small pendant-like fruits.

Sea Hibiscus Hibiscus tiliaceus is a somewhat untidy-looking tree with heart-shaped leaves and bright yellow flowers that turn maroon before falling.

© Sungei Buloh Nature Park

landmark

text and illustration
by joseph lai
conservation officer

invasion

Remember that monumental step on the moon? Astronaut Neil Armstrong leaping off Apollo 11to make that first footprint on the lunar soil in July 1969? I was 9 years old then. It was the talk of the town for as many weeks as I could remember. We kids were no doubt excited too. The moon landing added spice to our huge appetite for spaceships, aliens, Ultraman and the like. 'One small step for man, one giant leap for Mankind' meant nothing much to us kids then.

Of course we grew up and knew better. Man's two most entrenched aspirations since ancient time—to fly like a bird and to explore unknown frontiers—had taken a leap beyond the wildest dreams. The moon landing was a landmark victory for science, engineering and most of all, for the human spirit.

Yet as a biological entity, we human species are not alone in frontier exploration. Mudflats like those in Sungel Buloh were the monumental landing sites for sea-bound ancestors of plants that invaded dry land during the Silurian Period, 425 million years ago. With little more than rudimentary stem, ancient plants exerted their presence on land, leaving behind their familiar marine abode. 'One small stem for Plant, one giant leap for Plant Kingdom'- a landmark invasion from the sea that heralded land-plant evolution and aided the proliferation of land-dwelling creatures thereafter by becoming food for their sustenance.

The remains of many fossilized plants are still valuable resources in shaping the way we think about how present day plants are grouped (classified). Their presence also provided clues to ancient geography and climate of the earth. One good example is the humble nipah palm. Paleobotanists (paleo - meaning ancient) are unravelling more mysteries as new fossils are discovered.

But more significantly, paleobotany reveals to us that Nature can survive, and did survive for about 3500 million years, without Man. Modern Man's evolution about 2 million years ago pales in comparison. Yet within this last century alone, despite our achievements, Man had been the single most destructive force against Nature through habitat destruction, pollution, and over-exploitation. The greatest irony is that Mankind cannot survive without Nature.

If wishes were wings and time space, I would like to travel in time to see the ancient landscapes with a bird's eye view. Who knows, one day we might. For the moment, a walk in Sungel Buloh will reveal many links to the past. And if knowledge should inspire, let the spirit of aspiration be rooted in love for the only home we know and should cherish—the Earth.

... a walk in Sungei Buloh will reveal many links to the past

living fossil Belangkas or horseshoe crabs are not crabs as their name suggested. They are closely related to the spiders and scorpions. Horseshoe crabs, which are sometimes called king crabs, have hardly changed in structure for the last 400 million years. For this reason, they are highly regarded as a living fossil.

first flight Insects first appeared during the Carboniferous Period 345 million years ago. They were the first animals to take to the air, 150 million years before the birds. The giant Meganeura dragonflies, with a wingspan of over 27 inches, were one of the first. Though becoming smaller, the dragonflies remain the lords of the air as highly accomplished predators of the insect world.

nest surprise Crocodiles have been around for about 200 million years with little change. Their closest relatives are the birds. In fact, many crocodilians even gather grass to build nests. Crocodile brains are far more complex than those of other reptiles. Their hearts are almost as advanced as the birds and mammals.

first feathers
Birds are believed to have evolved from a crow-sized species of dinosaurs that appeared 150 million years ago. The first known bird is called Archaeopteryx, which means 'ancient wings'. It had lots of feathers, sharp teeth and a long rigid tail with two rows of feathers. Today's birds have no teeth or true tail. Instead, tail teattiers are attached to a reduced bony stump called the pygostyle.

small miracles Pollen of nipah palm is the one of the oldest known mangrove fossil found, dating back to 70 million years ago. Small miracles, considering how well they can be preserved. The toughness is attributed to the presence of sporopollenin in the outer coating, the exine. Fossil fruits of nipah have also been found in the clay of London and Paris, showing a much wider distribution than it is today.

ancient mariner Algae, bacteria and fungi represent the earliest life forms on Earth. The oldest known fossils dating back more than 3000 million years are the blue-green algae. Most algae are found in the sea either as plankton or as seaweeds. Seaweeds are simple, usually feathery or ribbon-like plants and have no system of veins or roots, leaves or woody parts. They may be anchored to the scabed or free floating.

forever fern One plant that has been widespread in both ancient and present vegetation of the Earth is the fern. Ferns are believed to have originated at about 400 million years ago and formed the main vegetation under the canopy of the tall prehistoric Clubmosses and Horsetails. Today, ferns number nearly 12,000 species and are still widely distributed throughout the tropics.

naked seed Naked seeds, not enclosed in a fruit wall, is a mark of distinction for the flowerless seed-plants called gymnosperms which include conifers. Examples of conifers are the pines, the giant redwood as well as Jati Laut (Podocarpus polystachyus) a native tree found above the high tide in our back mangrove. Early conifers first evolved at about 380 million years ago during the Devonian Period

© Sungei Buloh Nature Park

fat worries
of common redshanks

james gan
senior conservation officer
highlights the fat issue
of the common redshanks

Ever felt fat and heavy? For many people, becoming fat is not welcomed but for many birds it is crucial for their survival and vital if they are to eventually reach their breeding grounds to successfully reproduce and raise young.

The absolute weight and proportion of fat in migrant birds, such as the Common Redshank (Tringa totanus) fluctuate like a yo-yo throughout the course of a year. Lean in one month, a few weeks later, considerable weight can be put on mostly in the form of fat. Why would this happen? In a word—migration.

The fuel used by migratory birds for their journey is fat. Fat has many advantages as a fuel. It can provide twice as much energy per unit mass than any other biochemical fuel available (provides about 8 times the energy as provided by protein).

The field data, all of which were collected during bird ringing sessions, have contributed a bit more towards the understanding of the migration patterns and weight gain strategies of not only the Common Redahank but other migratory shorebirds. In particular, we have learnt more about the varying weights of the Red Shanks throughout the year and have obtainedsome indication of their weights close to their departure from the park during the northward migration. The information collected is invaluable tor the conservation management of Sungei Buloh Nature Park.

Laid down predominantly under the skin, fat is also deposited around the liver, the gut and between the wishbone. Additional weight gain also comes from the increase in the mass of the flight muscles. It is thought that the increase in muscle mass is in preparation for the strenuous long haul flight and also serves as a protein reserve for the energy demands of courtship and egg-laying at the breeding site.

The weights of Redshanks from a sample of about 370 (of birds measured between Jan 2000 & April 2001 in Sungei Buloh Nature Park) ranged from 79g to 178g with the 3 lightest birds at 79g, 85g and 87g. These lean birds, interestingly all juveniles, were taken in late Sep and early Oct during the autumn migration and may have just arrived at the park to take a break from their journey to a destination further south.

The 3 heaviest birds of 172g, 176g and 178g on the other hand were all recorded in early April and would likely be ready to depart for their breeding grounds that are thought to be in Tibet, Mongolia and Eastern Russia. Slightly more than 90% of the sampled birds had weights ranging between 100g and 140g for all periods of the year.

Maximum weights in general did not exceed 140g between Aug and Feb and there is evidence to suggest that the weights of Redshanks over-wintering in the Park remained stable during that period.

Records of Redshank weight suggest that fattening begins in March and continues in April. With one exception, Redshanks with weights above 140g were recorded only in March and April. The birds, apart from appearing fat, had also acquired varying degrees of summer plumage, another indication of reproductive preparation.

Some Redshanks from the sample have shown that they are capable of rapid weight increase. For example, weight gains of 18g and 23g have been recorded in autumn (Sept) for some juveniles over a period of 15 days in both cases.

More spectacularly, another juvenile weighing 98g that was ringed on 26 Sept and subsequently retrapped on 12 Oct had gained 28g over 16 days, an increase of 29% over its first recorded weight. If you are 60kg, imagine gaining weight at the rate of 1kg a day and ending up about 77kg in just over 2 weeks!

The retrapped Redshanks and their weight records support suggestions that some birds remain for a certain period in the Sungei Buloh area to replenish fat reserves used during the migratory journey south to escape the harsh winter conditions in the north. The evidence of a high mass gain rate also suggests a ready availability of food and could reflect the relatively favourable ecological conditions in the area although more study is required.

Comments or feedback? E-mail us.

references

Barter M. 1996. Ready! Steady! Go? A Crucial Decision for the Long-Distance Migrant; An Interesting Challenge for the Investigator. The Stilt 28, pp 32-42

Brooke M. & Birkhead T. 1991. The Cambridge Encyclopaedia of Ornithotogy pp 183-184. Cambridge University Press, Cambridge

Wells, D. R. 1999. The Birds of the Thai-Malay Peninsula, Vol 1. Academic Press, San Diego Science frontier/Pg 10 & 11.

Vol 8 No 2 Aug 2001 survivors of time: the horseshoe crab insect study tips on insect watching zonation: the landward mangrove fringe landmark invasion a walk in the past fat worries of common redshanks Allan Teo long-lasting companion of the park young naturalists of the park a nature journal javan munia		long-lasting companion of sungei buloh Allan Teo, 53, is a veteran volunteer guide of Sungei Buloh. An operations manager, he finds time to volunteer at the park with his son. the first step ... I was led to the Sungei Bulob Nature Park by my twin sons who were doing a school project about the Birds of Singapore way back in 1994. The staff extended such great hospitality that I wanted to contribute back to the park what they had shared with us. The serenity of the park and the different sightings also make Sungei Buloh an interesting place to visit. There is so much of Nature for us to relish here. the growing years ... We had less people and attractions in the earlier days and our group of volunteers was not as organised as today. We virtually trained ourselves from the books we read and by joining the Nature Society to upgrade our bird watching skills. Now we have more organised training for the new volunteers by fellow experienced ones. Sungei Buloh has grown from strength to strength from its infant stage to its present mature stage. With all the ideas and contributions from staff and volunteers, we are beginning to see the fruits of our labour. It is most heartening that the Management has been a very supportive bunch that looks after our volunteer group's interest. Being able to work with the staff makes my day. the satisfaction ... After all these years, I still enjoy my guiding sessions and I relish every moment that I spend with the groups that I bring in. It is very satisfying to know that I have contributed my share of knowledge to the small and unaware group that followed me in. the words of wisdom ... To our core volunteers, carry on the GOOD work. For all the rest of young volunteers, have no fear of leading any group. We have been through it before and we are all here to support you.
		© Sungei Buloh Nature Park

young naturalists
of sungei buloh nature park

linda goh
senior education officer

Boarding time came for 180 young participants to begin a learning journey of our natural heritage on World Environment Day.

On World Environment Day, 5 June 2001, National Parks Board together with Hongkong and Shanghai Banking Corporation Singapore launched a joint pilot project called the 'Young Naturalists Programme'. This programme was specially designed tor children to encompass the sense of adventure and achievement in the learning about our natural world.

Lady Bond, guest-of-honour,
presenting the Passport to Dr Leong, during the launch of the Young Naturalist's Pilot Programme

"How long do you intend to stay here?"

"Do you have anything to declare?"

"Your passport, please."

One by one, a group of young visitors were questioned as they proceeded to get their passports stamped by high-ranking officials at the immigration counters. They were about to enter the land where mangroves and wetland wildlife thrive and begin their journey of discovery into the wonders of nature.

Led by their assigned volunteer guides, 6 groups of children with their teachers and parents explored different parts of the park to complete their mission and earn the stamps for the activities they participated in. Some of these activities required the children to complete a word puzzle, write a poem, hunt for answers, and even build a nest!

The participants stand to earn 4 specially designed cotton badges when they complete all the activities in each category, namely, Nature Ramble, Nature Activities and Write Stuff, Thematic Trail and Natural Artist, as well as Special Mission.

Feedback from the pilot project will he collected to improve the programme before its full launch in November 2001. Look out for it.

nature journal
javan munia
(Lonchura leucogastroides)

by ramakrishnan r. k.
assistant park officer

The Javan Munia is a small, seed-eating bird found in Sungei Buloh Nature Park. It was introduced to Singapore from Indonesia in the early 19205. Often considered a pest by farmers, these birds are caught and sold in large numbers when they congregate in flocks during rice harvesting time. These birds are sometimes bought up by Buddhist devotees and released on Vesak Day.

The Javan Munia can be found in all kinds of cultivated areas and natural grassy patches in Singapore. Like all Munias, it feeds on the seeds of the grasses. Other species seen at Sungei Bulob include the Scaly-breasted, Chestnut and White-headed Munias.

This species is usually outnumbered by the Scaly-breasted Munia, which is often seen feeding on the tall grass at the fresh water ponds area at Route 3 or the vacant land beside the Visitor Carpark. However, this is about to change as the Javan Munia has successfully adapted to the man-made environment, nesting and roosting on buildings and potted plants.

In March 2000, I found a pair busy collecting strips of grass and heading towards a potted Boston Fern. They were building their nest on the potted fern that was hanging along the extended roof around the Visitor Centre. These birds had chosen a safe and sheltered place close to people. I further discovered that there was not 1 nest but a total of 20 nests of which 15 were in use.

The nest is built out of grass stems, stripped grass leaves or flowering heads woven into an untidy ball with a side entrance. The female lays from 4 to 5 white eggs and breeding usually starts from March to July.

note: Visitors are advised to leave nesting birds alone. When disturbed, these birds might abandon their nests which would be detrimental to the young.