Rough-necked monitor, flute monitor, harlequin
The rough-necked monitor is one of the most fascinating varanids. It is also among the most poorly studied of the
Asian species. This ancient-looking creature, very aptly ,
described by Georg Horn as reminiscent of "a black knight
from the Middle Ages", is very rarely seen in the wild, but whether this is on account of its
rarity or because it is very secretive is not certain. The rough-necked monitor inhabits
southern Thailand and Myanmar (Burma), Peninsular Malaysia, the islands of the Riau
Archipelago, Borneo, Sumatra and Bangka. There are no definite reports of this species from
Kampuchea, Laos or Vietnam, but traders claim to have received animals from central and
northern Thailand and suggest that they may occur in neighbouring countries (Wong, pers.
comm.). The type specimen was supposedly collected on the Philippine Islands but no
conclusive evidence that the animals occur there has been forthcoming (Taylor 1922).
Location data can be found in Mertens (1950), Harrison & Lim (1957), Brandenberg (1983),
Boonratana (1988), Jasmi (1989) and Bennen & Lim (in press).
This monitor is said to reach a maximum size of 180cm (Wong, pers. comm.) but the largest
specimen recorded measured 146cm TL (59cm SVL) and weighed just over 4kg (Harrison &
Lim 1957). According to Lekagul (1969)), in Thailand they wely exceed 100cm in length.
Wild specimens of about 40cm SVL in Malaysia weigh around 2kg (Lim, pers. comm.). The
rough-necked monitor is easily recognised by the large pointed scales that adorn the necks of
adults. The purpose of these scales is unknown, indeed, the entire natural history of this
magnificent animal is shrouded in mystery. They are found only in primary and secondary
rainforest and in mangrove swamps. Although they are said to avoid human settlements and
many life-long forest inhabitants are unaware of its presence, an adult has been found
sheltering in a disused washing machine at a small camp deep in the Malaysian rainforest
(Bennett & Lim in press). Direct observations of this species in the wild are scarce; Ladiges
(1939) encountered one in Sumatra resting on a log close to the water that ran up a tree to
escape him. Jasmi (19S9) and Nutphand claim that the animals feed mainly on the ground and
climb trees to escape from danger, often sheltering in tree hollows.
The diet of this species is very poorly known. Schnider (in Werner 1900) found only insects
in a specimen from Sumatra. Mertens (1942) believed that ants (and possibly termites)
formed a major part of the diet and were collected with the tongue. This is conftrmed by
Auffenberg (l988 and per's. comm.) who found termites, massive stick insects and tree
centipedes in six specimens from Malaysia. One examined by Brandenberg (l983) had a
stomach full of large cockroaches and grasshoppers and other from Surat Tharn in Thailand
had a stomach full of crabs (Nabhitabhata, pers. comm.). Five examined by Losos & Greene
(1988) contained frogs and their eggs, spiders, scorpions, crabs, cockroaches beetles and
orthopterans. The rough-necked monitor may be active throughout the year, but is most in
evidence during months of heavy rainfall (Nabhitabhata, pers. comm; Bennett & Lim in
Rough-necked monitors rarely become lame and show a healthy dislike of humanity. In turn
people often fear the lizard. According to Nutphand the species is often known as Ngu-HaoChang
(cobra elephant) in Thailand and are often attributed with Ihe ability to spit venom. In
Malaysia they are known as biawak serunai
(flute monitor) and on Borneo as biawak
(rotting tree monitor).
In captivity these monitors often have very nervous dispositions. Providing a very spacious
enclosure and allowing the animals to hide above the ground will help them to overcome
their shyness. Some authors (e.g. Sprackland 1992) have suggested that the animals are more
secure when kept in groups, but care must be exercised because some individuals act in a
very aggressive manner towards their conspecifics. Both Horn & Petters (1982) and
Nutphand report that young specimens like to bury themselves in damp substrates and that
they sometimes act dead when handled. In captivity they will accept a variety of invertebrates
(freshwater crabs, earthworms and insects), small mammals, birds and freshwater fish. They
need a constantly high temperature (no less than 23°C) and often respond to artificial rainfall
by commencing courtship behaviour. Females usually prefer to lay their eggs above ground.
Although eggs are often produced in captivity (up to three clutches per year each containing
up to 14 eggs (Mehaffey in Bennett 1993b)) they rarely hatch. Eggs laid by a recently
imported female were hatched successfuUy by Horn & Petters (1982) after 180-184 days
imcubation at 28-30°C. Hatchlings weigh about 21g and measure 25cm TL. Very young
specimens have yellow bands over the body that disperse with age. Whilst adults from
Thailand and Malaysia are often almost completely black, those from Borneo and Sumatra
may be brighter in colour.