Assorted vertebrates of Singapore:
Malesian Frog (Limnonectes malesianus) (Upper Left), Malayan Water Monitor (Varanus salvator) (Middle Left), Spanner Barb (Systomus lateristriga) & Two-spot Rasbora (Rasbora elegans) (Lower Left) & Asian Koel (Eudynamys scolopacea) (Right)
Malesian Frog (Limnonectes malesianus) (Upper Left): This is one of Singapore’s largest native frogs, growing up to 15 cm in length. Found in shallow streams, puddles, and swamps in forests, this frog is restricted to Bukit Timah Nature Reserve, Central Catchment Area, and the Western Catchment.
Malayan Water Monitor (Varanus salvator) (Middle Left): Singapore’s largest lizard, the Malayan Water Monitor is found in diverse habitats close to water, from mangroves and beaches to marshes and ponds, reservoirs and monsoon canals. Growing to 2 metres on average, its huge size means that it is often confused with its even larger relative, the Komodo Dragon (Varanus komodoensis). An excellent swimmer, individuals in the water are sometimes mistaken for crocodiles. Another misnomer is “iguana”, which are a family of lizards not native to the region.
Highly versatile and opportunistic, this carnivore consumes all manner of animal matter; any smaller creature is fair game, as are eggs and carrion. Monitor lizards have forked tongues like those of snakes, which they flick in and out of their mouths to detect scents. Malayan Water Monitors are also skilled climbers, and can be found basking on branches or hiding in tree holes.
The powerful tail is the Malayan Water Monitor’s primary means of propulsion in the water, and is also used like a whip when the lizard is cornered. The teeth are employed as weapons if necessary, and the sharp claws can do a lot of damage if the lizard is seized and struggles, but the Malayan Water Monitor is not dangerous and prefers to flee if approached.
Adult males are sometimes seen engaging in wrestling matches, rearing up on their hind limbs and trying to shove each other to the ground. The winner is the one that manages to pin down its opponent.
Although this lizard is adaptable and capable of living in urban Singapore, individuals in some areas might be at risk due to poaching for meat and entanglement in fishing gear.
Spanner Barb (Systomus lateristriga) & Two-spot Rasbora (Rasbora elegans) (Lower Left): Schools of these fishes can be found in clear streams and freshwater swamps in forests of the Central Catchment Area. Both of these species can grow up to 15 cm in length. Many of our native freshwater fishes are popular in the aquarium trade, and while poaching might pose a threat to some of our wild populations, habitat destruction and the spread of invasive species are likely to pose bigger threats to the survival of Singapore’s native freshwater life.
Asian Koel (Eudynamys scolopacea) (Right): This is a bird that can be considered ubiquitous, due to it being widespread and common in many habitats throughout Singapore. Found in wooded areas, mangroves, parks and gardens, and even in urban housing estates, where it feeds mostly on fruits and insects, this member of the cuckoo family is surprisingly hard to spot despite its size, as it is shy and spends most of its time in dense cover in the trees. However, its extremely loud and unmistakable call means that it certainly makes its presence known, sometimes to the annoyance of people, as koels can start calling before dawn, and continue late into the night.
The male is a dark glossy black, whereas the female is more cryptically patterned with brown and white. In the past, it was considered an uncommon winter visitor, but in recent decades, it has also become established as a breeding resident. Like many other cuckoo species, the Asian Koel is a brood parasite, laying its eggs in the nests of other birds and leaving them to raise its young. Several species of birds are known to serve as hosts, but in Singapore, the primary host is another common bird, the House Crow (Corvus splendens). Introduced to Singapore in the 1940s from the Indian subcontinent, the House Crow has flourished here, and this in turn has benefited the Asian Koel.
House Crow nests with newly-laid eggs are targeted by Asian Koels. A female koel may sneak in and lay her egg, which is almost identical to a crow egg in size and colour, when the occupants are away. It’s not confirmed whether she also removes any of the crows’ eggs at the same time, as is seen in other species of cuckoo. In some cases, koels will work in pairs. When a suitable nest is found, the male will position himself nearby in a prominent location, calling loudly. This prompts the pair of crows to give chase, and while they are away, this is the opportunity for the female koel, hiding in dense cover nearby, to deposit her egg in the nest.
The crows are none the wiser, and will care for the koel’s offspring as if it was one of their own. The koel chick hatches before the crows’ own young do, and its constant begging and faster growth rate means that the crows are likely to focus all their efforts on the koel, at their own brood’s expense. Even after fledging, the juvenile koel will continue to be fed by the crows for a few weeks.
These were some of the many specimens featured at the recently concluded Festival of Biodiversity 2014, which was held at VivoCity last weekend.