6000 years of emu mysteries unveiled

Scientists have tracked how climate change has moved emu populations through Australia.
Scientists have tracked how climate change has moved emu populations through Australia.

The emu - an iconic Australian bird, but also something of an enigma.

"They're so widespread, but we really don't know much about them," says Western Sydney University PhD student Julia Ryeland.

"How do you know how they're going to be affected by anthropogenic change when we don't even know basic things like lifespan?"

Ms Ryeland and other researchers at Western Sydney University and the University of Tasmania are the authors of a new study that sheds light on the mysterious bird.

The scientists investigated where emus are likely to live in Australia, as well as tracking where they have spent the past 6000 years and what will happen in the next 50 years.

They compiled emu spottings over the past few decades from the archives, matching the data with open source information about what conditions were like in those locations.

They discovered that climate is the most influential factor over where emus live, and that the birds are less bothered by things like habitat and urbanisation.

It turns out that emus like rainfall across most of the year, but are put off by heavy rainfall in summer.

The researchers used modelling to look at where emu populations were likely to have been from the mid-holocene -- around 6000 years ago -- to now, and then 50 years into the future.

Change in climate over the millennia led the flightless birds to move away from the eastern shores of Australia -- where they were often sighted even as late as European settlement -- westward and northward.

The emu is now found in healthy numbers across most of Australia, bar the uppermost parts of the Northern Territory, but in smaller numbers in the east.

Only one endemic population is known to remain in NSW east of the Great Diving Range -- a population on the north coast which is listed as endangered.

The climate there is on the fringes of what the birds relish. The suboptimal climate conditions might then leave the birds more vulnerable to feral predators and changes in land use, helping to explain their dwindling numbers, Ms Ryeland says.

But emus are survivors, even if a location does not have the right conditions for them.

"They're generalists and they're large-bodied," Ms Ryeland explains. "They can move really far distances quite quickly so they can recolonise different areas, and they feed off a really, really wide range of plants or invertebrates."

The good news is that man-made climate change is not likely to threaten emus in the next few decades.

"It looks like they're probably going to remain in similar areas in 50 years' time," Ms Ryeland says. "At the moment, it looks like the impact of anthropogenic climate change is going to be relatively small."

But the modelling showed that eastern Australia is likely to remain suboptimal for emus over the coming decades.

As one of only two emu researchers in the country, Ms Ryeland wants more funding to be put into understanding the endangered population in NSW.

"There's been no research done on this population at all," she says. "That makes it difficult to make really good management plans."

Ms Ryeland says the emu is a totem in a lot of Indigenous Australian cultures, and also appears on the Australian coat of arms.

"So it's a shame that we don't know more about them."

Australian Associated Press