Monday, 28 December 2015

NSS Kids’ Fun with Snakes at Pasir Ris Park (Singapore)

By Alastair Liew, age 10, Photos by Lena Chow

Frogs were croaking, crickets were chirping and nightjars were keening a jub-jub-jub call. We had to contend with mosquitoes and wet, muddy terrain. This did not deter the group of 30 odd kids and parents who had gathered at Pasir Ris mangrove boardwalk (located off Pasir Ris Drive 3 in Singapore) on 6 April 2013 at the dinner hour of 7 pm. Under the cover of darkness, we were here to search for nocturnal water snakes. Excitedly, we set off with flashlights, insect repellent and long-sleeved clothing.

A mudskipper in the spot light. Mudskippers propel themselves forward by curling their muscular body sideways, then pushing against the mud to move in skips.
At night, the mangrove swamp still teems with life. We spotted a handful of Giant Mudskippers (Periophthalmodon schlosseri) in their little territorial pools on the mudlfats. Mudskippers are fish that breathe through gills. Like amphibians, they can also obtain air through their skin and throat. When the tide is low, mudskippers adapt by storing air bubbles in their gills, much like a diver’s oxygen tank. Their eyes are perched on the top of their heads for a 360o view.    

The intricately patterned Violet Vinegar Crab (Episesarma versicolor) was well-camouflaged against the mossy mangrove trunk.
Our torchlights also picked up numerous Vinegar Crabs, also known as Tree Climbing Crabs (Episesarma spp). There are three species found in Singapore. These crabs climb up mangrove trees during high tide to avoid predators such as fish, kingfishers and monitor lizards. They can scale heights as high as 6 m. They are given the moniker of ‘Vinegar Crabs’ as Teochews traditionally eat them pickled in vinegar and black sauce. Tiny semaphore crabs, less than 1 cm long, are easily missed. They communicate their territorial rights by waving their pincers like flags. By using our binoculars, we could still pick them out. To our dismay, we did not see the fiddler crab. The male fiddler crab has an enlarged claw for mating and fighting while its smaller pincer is used for feeding itself.

The kids had satisfying close up views of an adult Dog-faced Water Snake.
As we moved along the boardwalk, Uncle Ding Li, Auntie Gloria and Auntie Lena pointed out the unique landscape of mangrove trees with their air-breathing roots interspersed with numerous Mud Lobster mounds. On the mudflats were Nerites, mangrove snails known as Belongkeng, Mangrove Hermit Crabs as well as flatworms.

We focused our torches on the tiny brackish streams that flowed seaward, the hunting domain of the water snakes. Finally, Auntie Gloria spotted the first Dog-faced Water Snake (Cerberus schneiderii) of the night, a 50-cm long sub-adult named for its protruding eyes. This individual was just 10-m from the boardwalk. It lingered in the shallow stream for a good five minutes, its wavy body swaying with the flowing water. Then it disappeared under a root.

Empty shells that could become home for the Mangrove Hermit Crab.
Without doubt, the highlight of the trip was another Dog-faced Water Snake, this time a one metre long adult. Uncle Hang Chong showed us its forked blue tongue and explained how it camouflages in the muddy water, waiting to strike out at unsuspecting small fishes. It can swallow prey much larger than itself. Later on, we came across another two Dog-faced Water Snakes, making it a haul of four snakes for the night.

Although we waved our flashlights at the trees and scanned the vegetation, we did not catch a glimpse of the elusive Shore Pit Viper, a venomous snake. You can be sure that the NSS Kids will be back to look for it, along with three other Water Snakes that inhabit Singapore’s mangroves, namely the Crab-eating, Gerard’s and the rare Cantor Water Snake!

NSS Kids Fun with Water Birds at Sungei Buloh Wetland Reserve (Singapore)

By Alastair Liew, age 9 & Ryan Liew, age 7

 The Liew brothers in action at Sungei Buloh Wetland Reserve.
Sungei Buloh Wetland Reserve (located off Neo Tiew Crescent in Singapore) is home to migratory birds and many other species of plants, animals and as we were to discover, lots of insects! We set off early on a cloudy morning on 3 February 2013 with a group of about 20 children and adults.

The mangrove swamp is a harsh environment that is boggy, oxygen-depleted and high in salt content. Mangrove roots have special adaptations. The Avicennia mangroves have pencil-like pneumatophores or air-breathing roots poking out of the mud to allow the direct absorption of oxygen. Prop roots in Rhizophora trees provide strong anchors in the mushy mud, preventing them from collapsing when the tide ebbs. These mangroves cope with the excess salt by secreting them on the underside of their leaves.

A Water Monitor Lizard well camouflaged in the mudflats.
Although we were too noisy and probably scared off the tree-climbing Vinegar Crabs, we had a monitor lizard that posed obligingly for photographs. We also saw cute mudskippers. One of the highlights was encountering the rarely-seen Mangrove Stingray. We counted five of them ‘flapping’ gently in the shallow brackish waters.

A little bird tweeted a secret in our ears: the best place to see the magnificent Oriental Pied Hornbill is by the men’s toilet! This is because the janitor feeds them papaya. We also spotted both Common and Collared Kingfishers, Little Egret, Grey Heron and even the Great-billed Heron, Singapore’s largest bird.

Along our hike, we caught sight of many magnificent spiders and their webs. The Orb Web Spiders weave huge, intricate webs that catch not only prey but even unwanted leaves and twigs. Sometimes the spiders have no choice but to abandon their homes when they become too cluttered with ‘rubbish’. The female Orb Web Spider rules the roost as it is many times larger than the male. Sometimes, she even cannibalises her mates after mating. We also spotted the St Andrew’s Cross spider, named for its geometric cross-like formation or stabilimentum through the centre of its web. The web reflects ultraviolet light, which in turn attracts insects to fall into the deadly trap.

We were delighted to see a feeding Oriental Pied Hornbill at close range. Photo courtesy of Dr Tan Kong Chong.
Katydids or bush crickets are related to grasshoppers and crickets. They are nocturnal. Perhaps that is why we found one hiding between the wooden floorboards in one of the observation hides. We then photographed what we thought was a Shield Bug with a beautiful cross on its reddish back. It turned out to be the Cotton Stainer Bug. We found out that the Cotton Stainer feeds on the seeds of the Sea Hibiscus growing by the seashore. It is considered a pest as it stains cotton red.

A Cotton Stainer Bug perched on the Sea Hibiscus. 
Do not be fooled by the cute, fluffy ‘cotton balls’ bunched up in a row on the branches of shrubs. These are Mealy Bugs, destructive pests that suck plant juices and can destroy crops. We thought that they resembled the Lallang when clustered together on a twig. We were surprised to see a plant with glossy, serrated leaves that looked just like the Christmas Holly growing right here in Singapore. It is actually called the Sea Holly and it flourishes by the mangroves, lobster mounds and river banks. But it is not related to the Holly used overseas as Christmas decorations, which has dark green leaves and red berries.

Our walk ended with the sighting of a superb Oriental Whip Snake. Mildly venomous, this fluorescent green serpent feeds on lizards, frogs and birds. Many of us exclaimed that it was a great start to the Year of the Snake!

Our Oriental Whip Snake resembled a green vine, blending perfectly into its surroundings.