Odatria
Varanus tristis (SCHLEGEL 1839)
Black-Headed Monitor, Freckled Monitor
 
subspecies: V. t. tristis (SCHLEGEL 1839)
V. t. orientalis FRY 1913
tristis
Varanus tristis
Purnululu Nat. P., WA
tristis
Varanus tristis
Alice Springs, NT
Varanus tristis is a member of the subgenera Odatria. The total length which can be reached is between 60 and 80 cm. Animals of the type species can grow much bigger than animals of the subspecies V. t. orientalis. The Canthus rostralis is common to both subspecies. Since the two subspecies differ from each other in the coloration and pattern clearly, I will describe them separately.
V. t. tristis can reach a total length of more than 80 cm. The major coloration of the Black-Headed Monitor is, how the name already says black. More or less clear yellow orange ocelli can be seen on the back. With some animals these ocelli have merged to an irregular reticulation. The tail is round in diameter and the coloration of the whole tail is deep brown till black. Its length is approximately 1.8 times is as long as SVL.

V. t. orientalis reaches a total length of approx. 60 cm. In this subspecies the coloration is reddish brown which is covered with numerous, irregular distributed bright ocelli with a dark central spot on the back. The head is uniformly red brown. A well visible eye line is visible on both sides of the head along the Canthus rostralis up to the neck. The tail is reddish brown to deep brown in the first half with occasional small cream-colored spots, and uniformly black on the last half. The underside is whitish. The head scales are small and smooth. The Supraocularia are distinguished by the greater Intraocularia sharply. The nostril is situated at the side and is a little bit closer to the tip of the snout than to the eye. 105-155 scale rows are around midbody. The tail is more or less round in diameter without an average keel and about 1.5 to 2.3 times as long as SVL.

orientalis
tristis
tristis
Varanus tristis orientalis
Ditmer, Qld
Varanus tristis tristis
Bourke, NSW
Varanus tristis orientalis
Eidsvold, Qld

 
Distribution, habitat and behavior

tristis

The distribution of Varanus tristis almost extends over whole Australia, except the outermost south and the southeast. The type species lives in the southwestern and central parts, while V. t. orientalis occurs in the northern and eastern parts of the distribution area (MERTENS 1942d, 1958, KEAST 1959, WORRELL 1966, BUSTARD 1968, SWANSON 1976, STORR 1980, STORR et al. 1983b, WILSON & KNOWLES 1988, HOSER 1989, COGGER 1992, EHMANN 1992). Overlapping of both subspecies in some parts of the distribution areas is possible. The transition of the subspecies is fluent in these areas. Also integrades can appear there (CHRISTIAN 1981). In the wild both subspecies feed mainly on insects and small lizards (LOSOS & GREENE 1988), PIANKA (1970c) observed an adult animal which approached a cockatoo nest on a tree to eat the eggs or the fledgelings there.
It is said for both subspecies that they are tree climbers. Own observations in the habitat which however do not disprove assertion completely either cannot confirm this completely. I could watch both subspecies in most various areas, I saw animals between Spinifex bushes on the ground without any trees available, some speciemen lived in crevices between rocks and others disappeared in burrows on the ground.

Keeping and breeding
 The captive husbandry of Varanus tristis with its two subspecies does not cause any big problems. These animals do not have any preferrences to the enclosure. In the wild they are found in many different habitats, so they will accept enclosures for ground dweller as well as enclosures for tree climber. So we can use different types of enclosures. To be able to offer the animals more action areas, it will be good to build some artificial rocks, made of styrofoam and epoxy resin, or cover the sides and the back of the enclosure with rough corkbark. Sand or wood chips are used as ground cover, some roots or thick branches complete the facilities. A water bowl, which should contain always clean water is essentiell.
Captive breedings up to the generation F2 of Varanus tristis orientalis have turned out well already repeatedly within the last years. Approximately six weeks after a successful mating 4-10 soft-shelled eggs were laid. The young animals hatch after an incubation period of 110 to 130 days in damp vermiculite or perlite. The temperature in the incubator should be between 27 and 29°C. When the babies hatch, they will have a total length of 19 cm and weigh about 4.5 g (EIDENMÜLLER 1989). The youngsters can be raised together in one enclosure for the first months, no aggressions were observed till now. As food we offer the monitors small house crickets, crickets, grasshoppers and occasionally newborn mice.
The offspring can lay again fertile eggs after about three years.
Nothing is published on captive husbandry of the type species Varanus tristis tristis till now. BENNETT (1993) reported of a young animal, which he discovered under the bark of a tree in the Great Victoria Desert in Western Australia. The young animal, which was obviously to be member of the black subgenus V. t. tristis had a cream-colored freckled pattern on the back. This coloration was almost identical to the coloration of young V. t. orientalis. Also THOMPSON (pers. comm.) has observed at a captive breeding of V. t. tristis, that the initial coloration and pattern reminds very strongly to that of V. t. orientalis, the young animals however changed color and showed the dark coloration of the parents after some time.
   
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