About Varanus tristis Schlegel, 1839
Varanus tristis Schlegel, 1839 has two distinct subspecies. The nominate subspecies V. t. tristis is the larger of the two, growing up to 80 cm in total length. Populations of this subspecies around Perth are completely black, while populations further north in warmer regions show increasingly lighter coloration. The smaller subspecies is V. t. orientalis, commonly called the freckled monitor, which reaches up to 60 cm long. It has lighter, more distinct coloration than the nominate subspecies, and a less spiny tail. Hatchlings of both subspecies are brightly colored, but only freckled monitors retain most of this coloration into adulthood. After reaching sexual maturity, which usually occurs around two years of age, males can be identified by a large cluster of spiny scales on either side of the vent. Females lack these obvious protrusions, and rarely have more than a small number of spines that are only slightly larger than the surrounding scales. Both sexes reach sexual maturity when they measure 20 cm from snout to vent. This is the most widespread monitor species in Australia. It occurs across the entire Australian mainland, and even lives on some northern islands including Magnetic Island. It is only absent from the southernmost and south-easternmost regions of the country. V. t. tristis occurs mainly in western Australia, while V. t. orientalis is mostly confined to eastern Australia. The two subspecies overlap in range (are sympatric) in some areas, including the east coast of Queensland. This is an arboreal monitor lizard. It is most commonly found near rivers in forests, scrublands, and woodlands, but it also inhabits deserts. It takes shelter in tight spaces such as loose bark, tree hollows, and rocky crevices. The breeding season occurs in November, when breeding pairs begin sharing the same tree. Females lay a clutch of 6 to 11 eggs in December, though clutches can be as large as 17 eggs. Eggs incubate at a temperature of 27 to 29°C, and hatch in February or March.
