Mournful goanna, black-headed goanna, freckled
goanna, racehorse goanna.
Varanus tristis tristis Boulenger 1839
Varanus tristis orientalis Fry 1913.
The mournful goanna is perhaps the most widespread of
the Australian monitor lizards. It is found throughout the
continent except for the extreme south and south-east and
occurs on many northern islands. Christian (1981) reports that they are absent from Victoria
and restricted to arid parts of western New South Wales. Fitzgerald (1983) records a
specimen from nonh-eastern New South Wales. According to Houston (1979) they are not
well known in South Ausualia. Low (1978) records their presence on Magnetic Island off
the northern coast of Queensland. Storr (1980) gives a list of locations in Western Australia
and Maryan (1989) found them at Peak Charles. Western Auscralia. I visited Peak Charles in
1991 , a few months after an extensive fire, and could find no sign of them. Records of V.tristiis orientalis
in New Guinea and adjacent islands (Menens 1950) probably refer to the V.timorensis
type animals discussed previously. V.tristis centralis
(Mertens 1957) is an
obsolete name for V.tristis orientalis
The name mournful goanna is somewhat misleading. It refers to the entirely black colouration
of the populations of V.tristis tristis
around Perth, Western Ausualia (tristis
Mournful goannas from warmer (i.e. more northern) areas become increasingly less sombre
in appearance. The freckled goanna V.tristis orientalis
was described from animals collected
on the Burnell River, Queensland. These animals lack the melanistic pattern of the mournful
goannas and can further be distinguished by the less spiny scales on the tail (Fry 1913;
Mertens 1958). Storr (1980) remarked that the few specimens he examined from Queensland
differed in scalation from Western Australian animals, but did not give details. In the
literature therefore, animals without black colouration tend to be described as V.tristis orientalis
. The subspecies appear to be sympaoic in many areas and both are found on the
eastern coast of Queensland (Christian 1981). Hatchlings of both varieties are brightly
coloured, but freckled goannas retain most of their juvenile pattern whilst in mournful
goannas the pattern darkens and is replaced with varying amounts of black as the animals
grow. Mournful monitors reach a slightly larger size than freckled monitors (about 80cm TL
vs. 60cm TL). In the deserts both sexes reach sexual maturity at 20cm SVL. A specimen
25cm SVL weighed 307g, another 25cm SVL weighed 150g and a hatchling of 7cm SVL
weighed just over 4g.
The mournful monitor is an excellent climber. Where uees are available the lizards spend
most of their time concealed beneath bark or in cree hollows. Where uees are absent, or are
occupied by other species, the goannas will live in rock crevices or under slabs of stone. Fyfe
(1979) notes that at Ayres Rock they are often seen around buildings. They are often found
along rivers and are known from forests, woodlands and scrublands but are also widespread
in desens. They are probably absent from the rainforests. Little is known about their way of
life in tropical Australia.
In the deserts of Western Australia mournful goannas shelter in Eucalyptus trees and move
directly from tree to tree, exploring burrows en route in search of food. They are most active
during the spring and often cover over
a kilometre per day accumulating large fat reserves to
sustain them through six or seven months of inactivity during the winter. Other lizards are
their main prey, including other goannas, skinks, geckoes and agamids. They often swallow
large agamids over a quarter of their own body weight and are able to swallow the heavily
protected thorny devil, Moloch horridus
. They also raid birds nests for eggs and fledglings
and collect a variety of invertebrates including orthopterans, beetles, ants and stick insects.
Mating occurs in November, when pairs of lizards have been found sharing the same tree.
Large numbers (6-11 but sometimes as many as 17) of small eggs are laid in December
which hatch in February or March, when the adults are relatively inactive. Nothing is known
of their nesting habits nor of the habits of juveniles, but very young specimens have been
found considerable distances from trees (Pianka 1971 , 1982, 1994; Losos & Greene 1988;
James, Losos & King 1992; Bennett 1993).
The thermoregulatory behaviour of the mournful goanna must be extraordinary. Body
temperatures as high as 47.3°C hav e been recorded in the wild (Pianka 1994)! The ability to
tolerate such high temperatures is very rare in the animal kingdom. In general however,
mournful goannas maintain lower active body temperatures than other desert goannas. The
amount of black colouration probably has a major effect on the rate of heating in this species.
It would be very interesting to compare the thermoregulatory behaviour of melanistic and
Outside the deserts mournful goannas may be less arboreal than their freckled counterparts.
According to Christian (1981) the former is more suited to a terrestrial existence than the
latter, on accounts of its larger size and greater speed. In areas of Australia where they
occur together Shine (1986) considered V.tristis
to be less arboreal than V.scalaris
a narrower range of habitats. Schmida (1985) listed the most important items of prey as frogs
and small mammals. Swanson (1976) claimed that insects, mice and lizards are preferred
foods. Both Christian (1981) and Fyfe (1979, 1980) report that V.tristis
can curl its tail over
its head and body when basking or walking. The purpose of this unusual behaviour is not
The name racehorse goanna has been used to describe several species of Australian monitor
lizard, including V.tristis
. This species may have most claim to the name, because they can
move at phenomenal speeds, especially when they are very warm. Their speed, arboreal
habits and secretive behaviour make them very difficult creatures to observe in the wild.
Pianka (1971) notes that this species drags its tail base along the ground when walking,
producing a distinctive trail. It would be interesting to investigate whether the lizards leave
any chemical clues to their presence by this means.
In captivity freckled monitors have reproduced in captivity on several occasions (Broer &
Horn 1985; Eidenmuller 1989; O'Dell 1992 & pers.comm., Lambertz 1995). Males of both
subspecies have clusters of spines on either side of the tail base which are very much reduced
or absent in females. The animals tolerate each other very well and a pair can be housed
comfortably in an enclosure with 1m2
of floor area. Large amounts of climbing space are
desirable but do not appear to be essential. A diet of various large insects and small rodents is
suitable, washed down with plenty of vitamins and minerals. Females should be gorged with
food throughout the breeding season to enable them to produce large numbers of strong,
healthy eggs. Darker animals in particular may benefit from cooler winters with a shorter
photoperiod. Mating occurs in the spring and two clutches of eggs can be laid within a
couple of months and up to four clutches can be produced over a year. They hatch after 95137
days at 27-29°C. Given good feeding (small insects and portions of rodents) they can
multiple in weight within three months and attain sexual maturity within 2 years.