Dingoes cleared of mainland extinctions
DINGOES HAVE BEEN UNJUSTLY blamed for the extinction of the Tasmanian tiger and the Tasmanian devil on the Australian mainland, a study has found.
In a paper published in the journal Ecology, researchers from the University of Adelaide say Aboriginal populations and a shift in climate are more likely responsible.
Both thylacines and devils lasted for more than 40,000 years following the arrival of humans in Australia.
Their mainland extinction about 3000 years ago was just after dingoes were introduced.
It has long been suggested they persisted in Tasmania because it was never colonised by dingoes.
Research associate Thomas Prowse said anecdotal evidence pointed to the dingo being responsible, along with its reputation as a ‘sheep killer’.
“However, most people have overlooked that about the same time as dingoes came along, the climate changed rather abruptly and Aboriginal populations were going through a major period of intensification in terms of population growth and technological advances,” Thomas says.
Hunting and climate change to blame
In their study researchers built a complex series of mathematical models to recreate the interaction between the main drivers of extinction, the long-term response of herbivore prey and the viability of the thylacine and devil populations.
The simulations showed that while dingoes had some impact, growth and development in human populations, possibly intensified by climate change, was the most likely extinction driver.
“Our models showed that dingoes could reduce thylacine and devil populations through both competition and direct predation, but there was low probability that they could have been the sole extinction driver,” Thomas says.
“Our results support the notion that thylacines and devils persisted in Tasmania not because the dingo was absent, but because human density remained low there and Tasmania was less affected by abrupt climate changes.”
Reintroducing Tasmanian devils to the mainland
Euan Ritche, a lecturer in ecology at Deakin University and recent Eureka Prize winner for his research on dingoes believes the study is an important new twist on the dingo extinction theory.
“It’s relevant because more and more people are talking about reintroducing Tasmanian devils to the mainland, and if you do that we need to be able to predict what will happen with dingoes,” says Euan.
However, he believes it’s difficult to identify with 100 per cent certainty what caused an extinction in the past due to the complex interactions in ecology. “I think this theory is just as likely an explanation for the extinction of the Tasmanian tiger and Tasmanian devil on the mainland as dingoes being to blame, but we have to consider the other option – that all three factors contributed to extinction,” he says.
“This team has taken a modelling approach and have made assumptions about how certain things would affect devils and thylacines, and it’s difficult to determine what caused the extinction and to what extent without being able to go back in time.”
Euan hopes that in the future the theory will be supported by observations of interactions between dingoes and Tasmanian devils on the mainland.