One of the apex land predators of the Northern Territory, a yellow-spotted monitor (Varanus panoptes) basks in the sun along a road in Kakadu National Park. As we approached, the goanna perked its head up curiously and ambled off into the grasses. Being so muscularly-built, its gait was comical with pronounced side-to-side swaying, large sweeping feet, and a stiff ridged tail. Before disappearing, the goanna performed its classic “tripod” stance— standing up on its hind legs and supporting its weight by the base of the tail. A quick surveillance of its surroundings and it wandered away.
V. panoptes and the perentie (V. giganteus) have remained as two of my favorite species of goanna since childhood (now also joined by Mertens’ water monitor [V. mertensi] and spotted tree monitors [V. scalaris]). Yellow-spotted goannas are intricately patterned, but from afar appear relatively camouflaged, especially when the ventral side is obscured. When confronted directly, they will rear up on their hind legs and inflate the gular pouch to expose the bright yellow coloration. During the breeding season, males will engage in combat with the same stance, wrestling and clutching each other with the forelegs. As a 3 to 5 foot long lizard, there are few predators out there willing to take on such a formidable animal (e.g. the occasional enormous olive python [Liasis olivaceus] or black-headed python [Aspidites melanocephalus]). Their claws are long and sharp, well-suited for digging burrows into the sandy soils, and a powerful tail whip and bite make them an unlikely prey item.
Sadly, goannas and many other species of Australian wildlife are experiencing dramatic population declines after the invasion of cane toads (Rhinella marina). Ingestion of a single adult cane toad and its toxins proves fatal for a goanna; populations of V. panoptes in particular have decreased over 75–90% along the Adelaide floodplain. Once an abundant species at Fogg Dam, yellow-spotted monitors and blue-tongued skinks alike are a much more rare sight along the wetlands.