Monitor Lizards in Singapore

We see Monitor Lizards around Singapore frequently, at Botanic Gardens, ay Sungei Buloh Wetland, among many other places, some big some small. We thought that the small monitor lizards are just juveniles, and did think about it twice.

Last Saturday we saw a monitor lizard high up in a tall tree at the Botanic Garden. Not really a surprise, we saw monitor lizards climbing trees quite a few times before. Comparing all the monitor lizard photos I took, I saw more monitors in the water than in the trees. I was curious to learn more about this shy but fearsome animals.

Clouded Monitor Lizard at the Botanic Garden

It tuned out that Singapore has 3 different species of monitor lizards: the Malayan water monitor, the clouded monitor, and the Dumeril's monitor. The Malayan water monitor is the most common and largest in size, it can grow up to 3 meters long. The other two are smaller in size, with Dumeril's monitor rarest, and easier to tell due to the dark and white strip colors on its body  

Dumeril's monitor

The Malayan water monitor, the clouded monitor are common, but hard to tell the difference, unless they are in the same location. The Malayan water monitor is much larger than the clouded monitor.

Here are the main differences between them according to internet search.

Feature	Clouded Monitor	Malayan Water Monitor
Size	Up to 1.5 m	Up to 3 m
Color Pattern	Cloudy, marbled blotches	Dark with yellowish bands/spots
Tail Shape	Slender	Thick and compressed
Nostril Position	Midway on snout	Near snout tip
Habitat	Forests, arboreal	Aquatic, urban areas
Behavior	Shy, elusive	Bold, often seen in cities

In my monitor lizard photos, typically a single monitor in a photo, the nostril position is the best indicator to tell the two monitors apart - clouded monitor has nostrils midway on its snout, Malayan water monitor has nostrils at the tip of its snout. We saw both species of monitors at both the Botanic Garden and Sungei Buloh wetland.

The monitors also wander about the residential area, one day we saw from our window, a monitor resting on the top of a chopped pine tree next to the apartment building!

a clouded monitor lizard climbing a tree at Thomson Nature Reserve

a Malayan water monitor resting on a tree at Sungei Buloh 

Malayan Water Monitor

Malayan Water monitor at Sungei Buloh

clouded monitor at Sungei Buloh

a clouded monitor resting on a chopped pine outside an apartment building

Monitor Lizards are solitary reptiles. The only time I saw a pair Monitor Lizards together was a few years back when two Lizards were fighting. 

So it was a big surprise to us to see two monitor lizards tangled together on a wooden platform near the entrance to the bridge over Keppel Wetland.  Quickly we realized that they were mating. I would like to see if they would quickly part their ways after mating. So we lingered around for a few minutes...but they remained tangled.  They might need hours to mate and then stay tangled to rest after intercourse. 

Less than 20 minutes later, on the way home, we were astonished to see one clouded monitor lizard followed another clouded monitor lizard from a tree canopy down to the ground,  and mounted on the latter. Another pair of monitor lizards copulate! 

From not seeing monitor lizards copulation to seeing two occurrence in a matter of 30 minutes !

Serendipity!!