The Rosenberg's monitor (Varanus rosenbergi) is an Australian species of varanid reptile found in southern regions of the continent.

They are large and fast predators with rugged bodies and long tails, having a combined length up to 1.5 metres, that will consume any smaller animal that is pursued and captured or found while foraging.

They resemble the closely related and widespread sand goanna (Varanus gouldii), to which they were previously allied as a subspecies, but distinguished by darker coloration overall, especially the markings at the tail tip and underside and the distinct black banding at the back and neck.

The dark tone at the head is marked with yellow dots above the mouth, and the yellowish cream background colour of the underside displays a blackish reticular pattern.

[8] The largest specimens are those found at Kangaroo Island, near the coast of South Australia, these are also darker than those on the mainland and possess a greater number of scale rows at the ventral side.

[12] They are highly active carnivores, able to pursue large prey, and opportunistic generalists whose diet includes birds, reptiles, mammals, eggs, and carrion.

This goanna has been observed eating road kill, including possums and wallabies, and consumption of these may account for a significant proportion of the mammal component of their diet.

The native Australian bush rat is likely pursued and caught, but the records of consumption of the western grey kangaroo and brush-tail possum is likely the discovery of their carcasses.

[5] The darker coloration of Rosenberg's monitor, a form of melanism, allows a greater degree of thermoregulation of their body in the cooler southern climates.

They periodically bask in the sun throughout the day, or when the opportunity arises, laying in the soil if it is warm or clambering on to branches to avoid a net heat loss; heath monitors are mostly found in their burrows during the coldest parts of the year.

[13][5] Rosenberg's monitor conserves its energy requirements during cooler seasons of the year, entering a state of torpor, but demonstrates the ability to voluntarily arouse itself during these periods.

[16] Reproductive behaviour, including guarding of nest sites, occurs during the summer over a four-month period of a sexually active adult's year, beginning before the December solstice and ending after the March equinox.

In December, potentially breeding members of both sexes begin making broad, deep, serpentine furrows in the ground termed “squidge marks”.

The pair stays in close proximity of each other for several days, often basking together with the male’s front and hind legs resting across the female’s back.

A study observing this species at Kangaroo Island found that hatchlings emerged at the point of the parents entry to the nest, and able to excavate themselves from their birthplace.

Their emergence corresponds with increasing warmth of the temperature outside the termitaria, and the hatchlings are observed at basking in the sunshine at the exterior and reoccupying the nest site during cold nights.

[4] Rosenberg's monitor is most common in the west, locally abundant in favourable habitat, and deeply fragmented in the east; isolated groups near Canberra and Sydney may represent a separate species.

[1] A subpopulation, with individuals somewhat larger in size, is found on Kangaroo Island, and a mainland population in South Australia is considered rare.

[1] The population in New South Wales, isolated and suspected to be a sister species, is found at high elevations that include occurrences above the snow-line in the mountainous regions of eastern Australia.

[4] The named distribution range of the widespread population of V. gouldi, due to a historically uncertain taxonomic description, was revised to exclude the southern coastal areas were this species occurs.