Monitor lizards at the Sungei Buloh Wetland Reserve

Posted by BESG on 21 November 07, Wednesday
Contributed by - see article -

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The Malayan Water Monitor (Varanus salvator) has made Sungei Buloh Wetland Reserve its home. Once relatively scarce, it is now common to see them along the main paths, in ponds and even around the entrance, so much so that the lizard is a minor attraction (above).

The lizard is an excellent swimmer, in fresh as well as saline waters. It can remain submerged in the water for up to half an hour. It can move with good speed relative to its size on land. It also climbs trees when the situation demands.

This is one of the larger lizard in the world and can grow to over 2 metres long. Shy by nature, it does not appear to be shy in the reserve. Most of the times it will back off when approached too near. However, visitors should leave the monitor lizard alone and not confront it, as larger ones can be dangerous and their bites can cause serious injuries.

It is a carnivore as well as a scavenger. Most of all, it is an opportunistic predator. It will eat almost everything that it can swallow. Its diet includes small mammals, snakes, lizards, young crocodiles, tortoises, birds and their eggs, fish, crabs and molluscs. However, it prefers carrion.

The lizard hunts by pursuing, rather than stalking or ambushing prey. And it regularly raids bird’s nests.

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It has been brought to our attention that its presence in such numbers at the reserve can be detrimental to nesting waterbirds.

The Little Grebe (Tachybaptus ruficollis) (left top) has never been sighted in the reserve. Can its absence be due to the presence of the lizards? The Lesser Whistling-duck (Dendrocygna javanica) used to breed in the area but no more. However, its absence, according to Wang Luan Keng, can be due to the presence of the snakehead (Channa sp.). Some years ago she saw a duckling being swallowed by the fish in a freshwater pond. The Common Moorhen (Gallinula chloropus) (left bottom) was sighted recently by KC Tsang but whether it is nesting in the reserve is another matter.

A pertinent question is, should the population be culled to a manageable level?

Other postings on Sungei Buloh Wetland Reserve: 1, 2, 3, 4, and 5.

Input by KC Tsang and YC, images by KC (montage: top left, bottom right; Common Moorhen), Chan Yoke Meng (Little Grebe) and YC (the rest).

References:
1. http://www.cyclura.com/modules.php?op=modload&name=News&file=article&sid=104
2.http://animaldiversity.ummz.umich.edu/site/accounts/information/
Varanus_salvator.html


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    Categories: Conservation

    7 Comments

    Comment by Hai~Ren

    Made Wednesday, 21 of November , 2007 at 5:09 pm

    Logically, we should encourage more crocodiles to live in the reserve. Show those monitors who’s the real king of the wetlands. =D

    Comment by Shih Tung

    Made Wednesday, 21 of November , 2007 at 8:25 pm

    I’ve seen Monitors even in very urban parts of Singapore over the last few years - Canal next to Zion Road Hawker Centre, roadside (!) next to Bukit Timah canal opposite Tekka market. Wasn’t sure at that time whether they were were escaped/released pets, but perhaps there has been a general resurgence of the population in all estuarine areas of Singapore. Do monitors tend to stay put in one area, or do they travel around ?

    Comment by Haniman

    Made Thursday, 22 of November , 2007 at 12:20 am

    These reptiles are traded in Singapore by the thousands.They come in from Indonesia and Malaysia mostly, in the form of skin.Singapore is biggest importer and re-exporter of raw and finished reptile skins and products. Varanus salvator is listed as Appendix II of CITES of which SG are a signitory.The trade is legal but the amount, as the years go by is,quite frankly disgusting.But they are rather abundant and even quite a pest in some places.The value of these reptile skins varies according to size,length and condition.Several grades are applied to a skin to match the right price.

    A lot of activists are against this trade.But if you look at it from a practical point of view, the trade in these reptiles, be it farmed crocs or wild caught lizards, are neccessary especially for producer countries which are mostly the third world nations. It provides income for the rural areas.I agree only the bigshot traders get the lion’s share but their businesses provide jobs for these rural folks who depend alot on the forest for a
    living. It is also a form of management for the species as too many of them can cause problems and like the elephants of East Africa,when u fail to cull or crop,over population eventually caught up with the species and wipe out the whole lot.

    It’s a little off tangent here.But I just like to share with you a different perspective on how the species is being utalised as with many other reptiles like crocs and pythons.

    Reference:

    http://www.unep-wcmc.org/citestrade/report.cfm

    Comment by kevin

    Made Monday, 26 of November , 2007 at 7:47 pm

    fascinating..
    would u happen to know what happens to pythons caught in sg?
    like here?
    http://naturespies.blogspot.com/2007/11/python-captured-in-bishan-park.html

    Comment by YC

    Made Monday, 26 of November , 2007 at 9:47 pm

    Previously, pythons caught by the police were sent to the Bukit Timah Nature Reserve and released. Later, they were sent to the zoo, so I was told… and were food for the animals. Not sure what happens nowadays.

    Comment by Haniman

    Made Tuesday, 27 of November , 2007 at 12:00 am

    Not all the animals donated to the Zoo are fit for consumption.Native species like varanus salvator or python reticulatus do get released if their health fits the bill. I think the Zoo is working with NParks regarding such releases.
    A lot of these were captured simply because they ’show’ too much of themselves and being at the wrong place at the wrong time.But where and when is right? When people see a rectic in the drain,they call the police and it has to be caught! If they see a water monitor swimming in a canal,they will call the authorities to catch the poor creature.People see barn owls roosting in buildings and they call pest busters.Paranoia or plain ignorance?I don’t know.

    Pingback by Bird Ecology Study Group » Water monitor lizard and waders

    Made Saturday, 29 of November , 2008 at 1:35 pm

    [...] abundance of Malayan Water Monitors (Varanus salvator) at the Sungei Buloh Wetland Reserve has made these lizards an added [...]

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