Australia: The Land Where Time Began

A biography of the Australian continent 

Spinifex Grassland Fauna

This vegetation type supports an unusual fauna, being dominated by termites, ants and lizards. In fact it has the highest number of lizard species of any place in the world, especially among geckos, dragons and some skinks. These grasslands occur on infertile soils with a large biomass and little grazing, so dead plant material becomes available for other herbivores. In this case, the termites, that can utilise such a low nitrogen food because of their gut bacteria.

In these grasslands, ants and termites are the dominant insects. Both being social insects, their colonies act as a buffer for both the extremes of temperature and of better times and the bad times. Because they have a secure base they can forage more widely than other insects, that are more like ephemeral plants, being present mostly in the better times. The birds tend to be nomadic and opportunistic.

Among the mammals, the red kangaroo is rare in the sandplains and dunefields. 3 known species of small marsupial live in the spinifex clumps. These are known as Ningaui to the Aboriginal People. There were several other small marsupials in this habitat, but since the replacement of the patch burning of the Aboriginal People by the more intense wildfires after the wetter years, they are either rare or extinct. Feral animals - rabbits, cats and foxes - accounting for many of them.

Rufous Hare-wallabies (Lagorchestes hirsutus) and bilbies (Macrotis lagotis) have declined markedly. They used to be common in thick spinifex around the margins of burnt patches where they could feed on the sprouting vegetation while it was still soft and easily digestible. With the change in fire regime, life got harder for them. They also had competition from rabbits and predation from feral cats to contend with. The rufous hare wallaby is about the size of a European hare, with shaggy, sandy-coloured fur. It was the most abundant and widespread macropod prior to the removal of the Aboriginal People from their traditional country. It is now critically endangered, being found only from 2 islands off he West Australian coast, Bernier Island and Dorre Island, and a small area of the Tanami Desert. The mainland subspecies is distinct, morphologically and behaviourally, from the 2 island populations. The only known population of as few as 20 individuals is centred on a palaeodrainage system. This Tanami population lives mainly in dense patches of spinifex (Triodia pungens), using it as shelter. It feeds on an adjacent area where the spinifex is less dense. In particularly dry times it moves further from its sheltering spinifex to feed on succulent shrubs in an area that is still within the palaeodrainage system. It has a varied diet, feeding on fruits and seeds when available, and grass leaves and stems, and when nothing else is available, spinifex, though it adds insects to its diet at these times.

The Rufous Hare-wallaby flourished in the conditions created by the practice of the firestick farmers, burning the vegetation a patch at a time, where there was a mosaic of vegetation structure and diversity.

Spinifex Hopping-mouse (Notomys alexis)

Sources & Further reading

Penny Van Oosterzee, 1993, The Centre - The Natural history of Australia's Desert Regions, Reed Australia.

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                                                                                           Author: M.H.Monroe  Email:     Sources & Further reading