More than gum leaves on the menu for the Monaro's koalas

Australian National University Research School of Biology PhD candidate Jessie Au was drawn to the area after koalas were observed stripping bark from eucalyptus trees.

Her research found the marsupials were eating the bark to fulfil their sodium requirements. The gum leaves of the harsh, high-altitude Monaro provided almost none of the essential nutrient.

"If you look anywhere else in their diet - any leaves, any other bark they have access to - they’ve almost got nothing, there’s almost no sodium in it, but in the bark of the specific trees that they pick, there’s a lot," Ms Au said.

"This is really exciting because it’s showing the koala who’s known to be very specialised can actually adapt to an unusual feeding behaviour to meet its requirements, and that’s really cool because typically when you have something that’s so specialised the flexibility ... is a lot less because you get so good at eating something you can’t really tolerate anything else."

The salt-seeking behaviour has been observed in other animals, including in African elephants, which lick cave walls for sodium, and in moose, which in some areas dive into lakes in search of particularly salty plants.

The unusual behaviour had likely helped koalas survive in the Monaro, Ms Au said. The region is one of two in NSW where the koala population is recovering.

Ms Au noted koalas - and other animals - were predicted to migrate to higher-altitude areas in response to increased temperatures brought by climate change.

"One of the scary things is we know these higher areas can be mineral-deficient and so the speed at which they can actually adapt to these new environments is going to be quite interesting because they have to adapt to having a poor nutrition environment," she said.

"It looks like it’s possible but we don’t know, given the timeframe of how climate change is happening, if they’re going to be able to adapt in the time that they need to."

Meanwhile, new signs have been installed between Canberra and Cooma warning drivers to watch out for koalas.

Two Thumbs Wildlife Trust trustee and Wildcare NSW koala coordinator James Fitzgerald said some had been killed on the roads in recent years.

The signs were also aimed at ensuring human safety, he said.

“You can imagine if you were a mum with kids in the car and a koala comes out in front, the kids go ‘don’t hit the koala’ and mum could swerve off the road and hit a tree," Mr Fitzgerald said.

The money for the signs was that left over from a grant aimed at developing a koala management plan.

Mr Fitzgerald said there were about 2000 koalas in the area.