Great Sandy-Tanami Desert

The Great Sandy-Tanami Desert ecoregion extends from Western Australia into the Northern Territory. It consists of three smaller desert regions: the Little Sandy Desert, located west of the Gibson Desert and east of the Great Northern Highway; the Great Sandy Desert, north of the Little Sandy in the northwest section of Western Australia; and the Tanami Desert, a rocky, hilly desert in the Northern Territory. Together, the deserts stretch across roughly 400,000 square miles (1.03 million square kilometers).

All three deserts are ecologically significant. Rainfall throughout the area is low, though high by desert standards; even the driest regions have annual precipitation of about 5 to 10 inches (12.7 to 25 centimeters). The desert-defining aridity is preserved not so much by a dearth of precipitation as by the extremely high evaporation rate due to the prevailing heat. Even winter daytime temperatures may reach the high 70-degrees F (20-degrees C) range.

The Sandy deserts contain several large ergs, also called dune seas or sand seas—broad areas of desert in which aeolian (windblown) sand covers a large part of the surface. These sands, important features of the desert ecosystem, are formed from aeolian processes that break down, erode, shape, and deposit rock and the resulting particles. These same processes help create desert varnish—a paper-thin coating of minerals (especially clays, manganese, and iron oxides) that forms on exposed rocks, sometimes combined with a microbial film of lichens and possibly microfauna, whose acidic excretions contribute to the ongoing breakdown of rocks into the salty soils of desert sand. The sands of both the Little and Great Sandy Deserts have a notable red hue.

Flora and Fauna

The dominant vegetation of the region is spinifex, an Australian desert grass of the Triodia genus (unrelated to coastal grasses of the genus Spinifex). The grass has awl-shaped, pointed leaves that store water during dry periods. The leaf tips are sharp and high in silica and have been known to injure people. First Nations people use spinifex to build shelters and fish traps, cook seedcakes, and prepare an adhesive used in making spears. Other plant species found here that have adapted well to the desert climate include the Livistona palm, native walnut (Owenia reticulata), and desert oak (Casuarina decaisneana). One plant species found in this region is Wickham’s grevillea (Grevillea wickhamii), a shrub.

Wildlife includes numerous species of lizards, such as the thorny devil (Moloch horridus), which is covered in spiny scales; the spines and ridges allow it to collect water from any part of its body, as when water condenses as dew in the night, as well as acting as a defense against predators. It moves oddly, rocking back and forth, conserving energy while searching for food, usually ants, in the spinifex sandplain. The devil can also channel water along capillary grooves between its scales to its mouth, drinking in rainwater before it has a chance to run off.

Predators of the thorny devil include some goannas (genus Varanus), an Australian monitor lizard with sharp claws and teeth and strong jaws; the largest goanna species in Australia, the perentie (Varanus giganteus), can reach up to about 2.5 meters (8 feet) long. The goanna principally preys on animals small enough to eat whole; when seen feeding on larger animals, it is nearly always scavenging, consuming carrion that it discovered already dead. The perentie (Varanus giganteus) is found in the arid desert regions of the continent. The Pogona genus of lizards, known as bearded dragons, is also found here.

The deserts are also home to the bilby (Macrotis lagotis), marsupial carnivore mulgara (genus Dasycercus), marsupial mole (Notoryctes caurinus), rufous hare-wallaby (Lagorchestes hirsutus), red kangaroo (Macropus rufus), desert tree frog (Litoria rubella), spencer’s burrowing frog (Limnodynastes spenceri), desert spadefoot toad (Notaden nichollsi), feral camel (Camelus dromedarius, introduced to Australia in the 19th century), and the dingo (Canis lupus dingo).

Many desert species are specially adapted to the region. The red kangaroo’s gait, for example, is an energy-efficient way of traveling from food source to food source, and minimizes the amount of time the kangaroo’s footpads are in contact with the hot daytime sand.

Significant endemic mammals in the Great Sandy-Tanami Desert include the long-tailed planigale (Planigale ingrami), the smallest of all marsupials and one of the smallest mammals at less than 2.5 inches (6 centimeters) long; the western chestnut mouse (Pseudomys nanus); and the delicate mouse (Pseudomys delicatulus). The Tanami, along with the rest of the region, is also home to the rare grey falcon (Falco hypoleucos), typically found in the Triodia grasslands and Acacia shrublands. The grey falcon is one of Australia’s mystery birds, rarely seen.

Human Impact

While the Great Sandy-Tanami Desert biome remains largely intact, concerns over negative environmental impacts stem from overgrazing in some areas, mining activities, tourist activities, and changes in native and endemic species due to the intended or unintended introductions of foreign plant and animal species. Feral and invasive animals cause great damage to the ecosystems. The Australian Outback had an estimated 1 million feral camels in 2008–10. The animals eat more than 80 percent of available plant species, destroying ecosystems. The government’s National Feral Camel Action Plan brought camel numbers down to an estimated 300,000, but experts predicted that camels could double their population in just eight years. Camels are just one of many invasive species threatening the desert. A study conducted at the Arid Recovery Reserve in South Australia found that removing feral cats and foxes led to significantly higher populations of native small mammals, demonstrating ecological recovery when invasive predators are controlled. Martu and Kiwirrkurra Rangers collaborated to manage feral camels, cats, and foxes in remote areas of the Great Sandy Desert, reflecting ongoing efforts to control invasive species.

Also, of concern are changes in the weather caused by global warming and climate change. Heat waves, drought, and fires have ravaged the continent of Australia, including its deserts. Experts fear that the situation will worsen in the future. Fires have always been a natural part of Australia; however, human activities have caused more frequent fires, giving the environment little time to recover between fire occurrences.

Bibliography

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Fishers, Rohan, and Neil Burrows. “Professional Firefighters ‘Astounded’ by the Scale of Fires in Australia Right Now.” ScienceAlert, 7 Dec. 2021, www.sciencealert.com/professional-fire-watchers-astounded-by-the-scale-of-fires-in-australia-right-now. Accessed 14 Feb. 2026.

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