Bush Heritage Landscape Ecologist Phil Cullen describes our newest reserve.
A major arid-zone property will be the next Bush Heritage reserve. It's a haven for desert wildlife, with river floodplains, dune systems, clay pans and ephemeral and semi-permanent wetlands. You can help us to protect this outstanding property now.
It was over two years ago that Bush Heritage was first alerted to Ethabuka, a 214 000-hectare pastoral lease on the northern edge of the Simpson Desert.
Angus Emmott (Channel Country grazier and long-time campaigner for the Cooper Creek) told me an intriguing tale about a river that flowed only about once a decade and died as a series of waterholes in the sand dunes. He talked of ephemeral lakes that could support huge numbers of waterfowl, vast areas of habitat for a suite of desert mammals that were rapidly disappearing from the landscape, and pressed his point by commenting on the lack of reserves in the Channel Country.
This property, he said, was in very good condition and had seen little development as a cattlegrazing lease.
With its apparent lack of threats my initial reaction was to wonder why Bush Heritage would consider buying such a property. However, after talking to Dr Chris Dickman, a researcher at Sydney University whose work on the mammal fauna of the region and on this property spans more than a decade, I was convinced of the importance of protecting this outstanding place. His information was remarkable.
The desert wildlife on this western Queensland property is largely intact. With 198 species, the property has a significantly higher diversity of animals than the adjacent Simpson Desert National Park and higher densities than the more heavily stocked neighbouring properties.
Twenty-six native mammal species have so far been recorded on the property. The community of 14 small to medium-sized mammal species is exceptionally rich and includes the small carnivorous mulgara that is listed as nationally vulnerable. Also found there are the desert short-tailed mouse, the spinifex hopping mouse, the desert mouse and the charming sandy inland mouse which is also present at Bush Heritage’s Charles Darwin Reserve, WA.
The survival of these species on Ethabuka is largely explained by the near absence of rabbits. The country is probably just too hot and dry for them. Fewer rabbits have meant a healthier ecosystem, less competition for food and importantly fewer foxes and cats, which often establish along with their rabbit prey.
Chris went on to say that the property is also considered to have one of the richest reptile faunas in Australia. Fifty-four reptile species have been recorded, including the woma (a rare desert python) and a small desert-dwelling skink Ctenotus ariadne, both of conservation significance.
One hundred and twelve bird species have been recorded, including the Australian bustard, painted honeyeater, yellow chat, and chestnut quail-thrush, all of which are listed as ‘threatened’. Six species of frogs have also been found.
Vegetation and wetlands
The vegetation on Ethabuka is diverse, with 18 major plant communities and 200 species identified so far. Around 36 200 ha of the property is on or adjacent to the flood plains, the type of country that is prized for cattle production and thus unreserved or poorly reserved.
Most importantly, the property extends along a major environmental gradient and incorpo-rates country from the heart of the Simpson Desert to permanent or semi-permanent waterholes on the flood plain. This gradient is not represented in the Simpson Desert National Park.
The ephemeral wetlands and the semipermanent Pulchera Waterhole on Ethabuka are part of a complex of features on the junction of the Mulligan River and Wheeler Creek that have earned the area listing as a wetland system of national significance.
The wetlands spring to life after big rains or with floods coming down from higher in the catchment. They provide habitat for large numbers of waterfowl. The Pulchera Waterhole dries up only during the most severe droughts, so remains a focus for cattle grazing.
Equally important is the Field River, a normally dry watercourse that on rare occasions flows down from higher country to the north-west and out into the heart of the Simpson Desert. It delivers lifegiving water to a string of waterholes, stands of red gums and coolibahs and extensive grassy flats.
This ecosystem extends many kilometres into the Simpson Desert dune field, creating an oasis for a suite of arid woodland species. Again, cattle concentrate here when water is available.
Three factors have been identified as the primary causes of the loss and decline of mammal species and ground-nesting birds in arid and semi-arid Australia: the loss of variability in the vegetation from changes to the pattern and intensity of fires, degradation of habitats as a result of over-grazing by stock and feral animals and, particularly, the spread of rabbits and their predators, cats and foxes.
Fire is a major threat. In recent times the regional fire regime has changed from one of small-scale, frequent and low-intensity fires, as practised by the Aborigines (resulting in an in-tricate mosaic of varying vegetation structure across the landscape), to one of infrequent, broad-scale, high-intensity fires that result in the loss of variability in the vegetation structure. This leaves large areas unsuitable for small mammals and other fauna.
In recent years a number of high-intensity fires have burnt out hundreds of thousands of hectares across the Simpson Desert National Park and parts of Ethabuka. Foxes and cats moved in after the most recent fire to prey on the exposed small mammals. However, as the vegeta-tion has begun to recover, the fox and cat numbers are again declining.
Over-grazing by cattle can have an effect similar to fire by removing the protective ground cover. It also prevents grasses from setting the seed that's an important food for many small mammals and birds. The gradual expansion of grazing into areas previously considered marginal for cattle is a concern for the long-term viability of small-mammal populations in these arid areas.
The station neighbouring Ethabuka is now developing new water points throughout most of the areas that currently support little or no stock. Regular grazing and the provision of the drinking water needed by predators mean that the quality of these habitats, which have probably been refuges for small-mammal populations up until now, is likely to decline.
The long-term impacts of grazing in these remote regions are only now beginning to be reported in the conservation literature. Regions such as the Kimberley, Cape York, the Top End and the Gulf Country, which we once considered to be in a more or less natural condition, are now showing signs of species loss and land degradation.
When I visited Ethabuka in August 2002 western Queensland was in the grip of the severest drought in living memory. Throughout the region much of the sheltering ground cover had gone. The need for a refuge area for the wildlife was startlingly obvious.
Despite a long pastoral history on the eastern side of the property, Ethabuka has largely survived any major degradation of habitat. Grazing has concentrated around the ten or so bores in the east while the western half has been grazed only in years when good rains have filled surface pools. Some areas have never held stock.
With its exceptional small mammal populations, Ethabuka needs active control of predators and sensitive fire management to provide a long-term wildlife refuge for the Channel Country. Allowing it to develop as a fully productive pastoral lease will not guarantee its future for conservation.
This new property represents just one of the many opportunities we must seize if we're to secure a future for our unique wildlife and landscapes and avert the fate that has befallen much of the south and east of the continent. You have the opportunity now to help us purchase this wonderful place, and I ask that you give generously. It is a chance we must grasp with both hands.