Dingoes reshape the landscape

A comparison of conditions in the outback on either side of Australia’s dingo fence has revealed that extermination of predators affects not only the abundance of other animals and  plants,  but also reduces the quality of the soil. The UNSW study indicates greater control of kangaroo numbers is needed across a third of the Australian continent where dingoes are rare, to reduce damage on ecosystems.

“We have shown the presence of dingoes is linked to healthier soils, because they suppress the numbers of kangaroos that graze on the vegetation,” says senior author of the study, UNSW Associate Professor Mike Letnic.

The research by Letnic and his honours research student Timothy Morris has been published in the journal Proceedings of the Royal Society B.

The dingo fence, erected to keep dingoes out of eastern Australia, extends approximately 5,600km across South Australia, New South Wales and Queensland.

Dingoes are common on the western side of the fence, but rare on the other side, due to intensive control measures including poisoning, trapping and shooting. This latter area includes most of New South Wales and Victoria, and southern Queensland and southern South Australia.

The researchers studied four sites – a national park site and a pastoral site on each side of the fence in the Strzelecki Desert. They drove along outback dirt tracks at night for four years to count dingoes and kangaroos. They also collected dingo scats to determine what they ate, and measured levels of phosphorus, nitrogen and carbon in the soil.

Kangaroo numbers were high at the two study sites on the “inside” of the fence where dingoes were rare, with just one dingo and 3,245 kangaroos spotted, compared with 85 dingoes and only eight kangaroos at the two study sites “outside” the fence.

The researchers also found that where dingoes were rare, large numbers of kangaroos overgrazed vegetation cover, leading to lower levels of phosphorus, nitrogen and carbon in the soil. 

“Our novel finding goes against the conventional wisdom that apex predators like dingoes have little impact on soil,” says Letnic. “We show that allowing dingo populations to increase could enhance the productivity of ecosystems across vast areas of the country by reducing herbivore numbers.

“We need to rethink the idea that kangaroos have benign impacts on ecosystems. Kangaroo numbers are very high across the approximately one-third of the continent where dingoes are rare, and are having damaging impacts on soils and vegetation,” he says.

Pure Australian desert dingo Sandy Maliki. Photo: Barry Eggleton.