Heath Goanna
Goannas are our last remaining large, native, terrestrial predator in southern SA and they need our help!
About goannas
Also known as Monitor Lizards or Varanids, there are 28 species of goanna in Australia.
Three large goanna species occur in south-eastern South Australia; the Heath Goanna, Sand Goanna and Lace Monitor. The Heath Goanna and Sand Goanna are similar in size and patterning and can be easily confused. The Lace Monitor is larger, easier to distinguish from the other species and has a more restricted distribution in South Australia.
Goannas are predominately terrestrial predators that are generally active during the day. They feed on carrion, small birds and mammals, insects, spiders, small reptiles and eggs.
Conservation Status
The Heath goanna, also known as Rosenberg's goanna, is classified as Vulnerable in South Australia.
Regionally, it is classified as Endangered an the Mount Lofty Ranges, Northern and Yorke Peninsula, Eyre Peninsula, Murray Darling Basin and South East regions.
The Heath Goanna (Varanus rosenbergi) was once common in many higher rainfall, cooler areas across southern Australia but is declining. It now occurs in mostly small, isolated populations in WA, SA, VIC and NSW.
Why is the Heath Goanna Endangered?
Habitat loss, degradation and fragmentation through land clearance and grazing has reduced the amount of suitable habitat available to the Heath Goanna. They need large areas of native vegetation to find enough food and maintain sustainable populations.
Removal of termite mounds (used to incubate eggs) and fallen trees and logs (used for shelter) from the bush and grazing land, reduces vital habitat for these goannas.
Predation by cats, foxes and dogs
High road mortality, particularly in areas with sealed roads (with higher speed limits) and extensive road networks
Where do they live?
The Heath Goanna generally occupies heath, wet and dry forest and temperate woodlands usually with sandy soils and termite mounds present. They will utilise adjacent grazing land to find food, shelter, a breeding partner and to move between patches of remnant native vegetation.
Ecology
They have large foraging areas ranging between 80 and 1000 hectares. The female lays its eggs during summer, burying them in a termite mound. The termite mound maintains a constant and correct temperature and humidity for incubation throughout the winter. Females, and often their male partners, actively guard their new nests from predators for up to three weeks until termites have had time to repair the mound. This conceals and protects the eggs. The young hatch in spring and less than one in 12 survive their first year. Those that do survive may not reach breeding age for up to nine years.
What do the Heath Goanna and Sand Goanna look like?
Both species are similar in size and appearance making identification difficult. Adults of both species have total lengths ranging between 1 m and 1.5 m and both vary in colour and pattern.
Distinguishing features
Tail:
The tails of both species are usually clearly banded. The clearest feature that distinguishes between the two species is the colour of the tail tip:
The Heath Goanna’s tail tip is the same as its body colour, usually grey (with or without obvious banding)
The Sand Goanna generally has a pale tail tip (often yellow) in contrast to the rest of the tail which is darker with lighter bands
Neck:
The Heath Goanna has darker bands on the neck that are curved (like a collar)
The Sand Goanna has dark bands on the neck that generally run parallel to their neck.
Body:
both species have a range of pale yellow or white spots over their body and legs; these are usually arranged in bands:
The pale spots on Heath Goannas are small compared to the often bold, large blotches that occur on the Sand Goanna (particularly on the legs).
Distribution in South Australia
While Heath Goannas are still relatively common on Kangaroo Island, they are also declining there. Isolated populations occur elsewhere in the state
The Sand Goanna is widespread throughout the state, only being absent from cooler, wetter areas (the far south-east, Kangaroo Island and high rainfall areas of the Mount Lofty Ranges). They probably only occur in very low numbers on southern Eyre Peninsula and may be absent from parts of the west coast and the Nullarbor.
Maintenance plan submitted