Did dingoes kill the thylacines?

3 May 2012

A new theory states dingoes may have contributed to the extinction of the thylacines.
A new theory states dingoes may have contributed to the extinction of the thylacines.

Direct attacks by introduced dingoes may have led to the extinction on the Australian mainland of the iconic marsupial predator, the thylacine, a new study involving University of Sydney researchers suggests.

A comparison of museum specimens by Dr Mike Letnic from the University of NSW with University of Sydney colleagues Dr Melanie Fillios from the Department of Archaeology and Dr Mathew Crowther from the School of Biological Sciences has found that thylacines on mainland Australia were smaller than those that persisted into modern times in Tasmania, and significantly smaller than dingoes. The last known thylacine, which has also been known as the Tasmanian tiger, died in 1936.

Measurements of the head size and thickness of limb bones of the semi-fossilised remains of thylacines and dingoes from caves in Western Australia have revealed that, on average, dingoes were larger than thylacines. They were almost twice as large as female thylacines, which were not much bigger than a fox.

The findings are published in the journal PLoS One.

Aware of old reports that mainland thylacines were smaller than Tasmanian ones and that modern ecological studies show that larger predators frequently kill smaller predators, the researchers decided to test the hunch that dingoes were actually larger than thylacines and caused their extinction by killing them in direct confrontations.

"Recent studies have shown that foxes are suppressed in areas that have many dingoes, and it appears that the dingoes kill the foxes. Hence we believe that the same mechanism occurred 3500 to 5000 years ago with dingoes killing thylacines," says Dr Crowther.

Dingoes were probably introduced by human seafarers, and are likely to have caused the extinction of the Tasmanian devil from mainland Australia (devils are still found in Tasmania, which does not have dingoes).

There has long been debate over what caused the extinction of the thylacine from mainland Australia. Because thylacines were much larger than dingoes, direct confrontation between the two species was discarded as a hypothesis for the thylacine decline.

Another hypothesis is that competition between the two species may have been the cause, however competition is not thought to be a strong driver of extinction.

Recent studies suggest that dingoes now play an integral role in maintaining healthy balanced ecosystems by limiting the populations of herbivores and smaller predators, a role that was once filled by the thylacine.

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