The rufous bettong, or rufous rat-kangaroo rat-kangaroo, is one of many small mammals negatively impacted by the arrival of European settlers in Australia. Photo by Mammals of Australia John Gould / Public Domain
Feb. 18 (UPI) -- Australia is bleeding mammal species. The island continent's mammal extinction rate is the largest on Earth. But in Australia's desert, the return of indigenous hunters has helped restore ecological balance and slowed the loss of mammals.
According new research by Rebecca Bliege Bird, a professor of anthropology at Penn State University, the removal of humans from the landscape precipitated the loss of small mammal species in Australia's desert.
"I was motivated by the mystery that has occurred in the last 50 years in Australia," Bird said in a news release. "The extinction of small-bodied mammals does not follow the same pattern we usually see with people changing the landscape and animals disappearing."
During the mid-20th-century, an Australian Aboriginal people known as the Martu were removed from their homeland, Australia's Western Desert, to make way for a missile testing range. In the 1980s, Martu people began returning to their ancestral lands.
Bird's research showed the rate of mammalian extinction increased when the Martu left and decreased when the Martu returned. Bird and her colleagues closely examined the region's food webs before, during and after the Martu's removal, absence and return.
As part of their hunting and gathering practices, the Martu regularly burn the land. The hunting fires boost the patchiness of desert vegetation and limit the spread of wildfires. Scientists determined the diminished risk of large fires benefits the dingo, monitor lizard and kangaroo, three iconic Australia species.
When the Martu were relocated, the region's dingo population plummeted. The native dog helps control invasive species populations, including cats and foxes. Invasive predators are one of the main causes of mammalian extinctions in Australia.
With the Martu and dingo gone, invasive species flooded the landscape. As a result, the numbers of many small species plummeted.
"The absence of humans creates big holes in the network," said Bird. "Invading becomes easier for invasive species and it becomes easier for them to cause extinctions."
The negative impacts of the Martu's hunting and gathering practices are minimal, research showed, while the aboriginal group's controlled burns offer significant ecological benefits.
Bird presented her findings over the weekend at this year's annual meeting of the American Association for the Advancement of Science held in Washington, D.C.