‘Calling out’ the koala legends

By 
Amy Edwards

11 November 2025
4 min learn

There are components of Australia the place koalas are talked about like city legends.

Older folks, who’ve lived in these areas for generations, inform tales about recognizing the little Aussie icons in a favorite tree or listening to them bellow within the useless of the evening.

Meanwhile, enthusiastic households can spend hours strolling by means of that very same bushland, peering at each nobby tree development within the hope of it being a koala, solely to finish up with sore necks and complaining kids.

Enter the acoustic recorder.

It’s been a recreation changer for our National Koala Monitoring Program, which has realised its newest estimates for this yr. The estimates present a rise within the estimated numbers throughout Australia, which is nice information for our koala pals.

Much of the change within the inhabitants estimate is pushed by extra survey effort, extra information, mannequin enchancment and extra delicate surveying strategies resembling thermal drones and acoustic recorders.

These trusty little recording units can inform us with excessive certainty whether or not koalas are current in an space or not.

With mating season underway in Queensland, our researchers have been hitting the highway and have deployed about 150 acoustic recorders in Central and Northern Queensland. This might be adopted by components of South Australia all through November and December.

These journeys may end up in researchers confirming koalas past their anticipated vary. Last yr they confirmed koalas on the fringe of a spread in Western Queensland. The male koalas had been recorded bellowing close to the small Queensland township of Quilpie, 478 km West of Roma.

Counting koalas

Koalas could be tough to identify from the bottom. They are most energetic at evening and infrequently relaxation excessive in timber in the course of the day.

To precisely estimate the variety of koalas in Australia, CSIRO’s National Koala Monitoring Program, along with companions, deploys a variety of survey strategies together with strolling surveys, drone-based thermal imaging, acoustic monitoring, historic surveys and citizen surveillance through Apps resembling Koala Spotter.

CSIRO ecologist Dr John McEvoy mentioned acoustic recorders had been a extremely necessary instrument in CSIRO’s toolbox to make sure correct, site-appropriate information assortment for long-term koala conservation.

“We’ve been using the acoustic recorders more or less from the start, but we’ve really ramped up our usage of them in the past year,” he mentioned.

“A lot of the areas where we’re studying are scarcely populated by koalas. We are pretty sure koalas are there, but looking for them on foot is going be a huge effort. So instead of doing that you can put out a smaller number of recorders and leave them recording for you know, two weeks or even more. And if a koala calls somewhere in those two weeks, you’re going to get them.”

Statistically talking, a two-week window is a bit of on the beneficiant aspect and most koalas, if current, might be heard inside 10 days.

And after they name, there isn’t any mistaking them.

The trusty male koala is perhaps small and cute, however it bellows like a rock star.

The koala mating name

Male koalas bellow to draw females in addition to to intimidate different males and get them to go away the speedy space.

“The male bellowing is booming and travels quite far away,” Dr McEvoy mentioned.

“It’s good that it’s so distinctive and so loud because that really does help us identify the koalas on the recorders.”

Male bellowing typically peaks round midnight, so recorders are often set for taping from simply after nightfall till simply earlier than daybreak.

This additionally avoids the daybreak and nightfall intervals, the place there’s a whole lot of basic noise from birds, frogs, bugs and different animals. The feminine koalas do vocalise, often when the males are fairly near them, however it’s a way more high-pitched sound and more durable to choose up on recorder.

How the recorders work

The omni-purpose recorders should not low cost (about $600 {dollars}) however their skill to collect info is big. A analysis crew on the NSW Department of Primary Industries (DPI) developed a koala name recogniser and generously made the software program freely out there for different koala researchers to analyse their audio information.

The recorders are often connected strapped to a medium sized tree, round shoulder top, and are fairly small and camouflaged. They are programmed with a recording schedule to modify on and off and could be managed with a telephone app.

Next steps

The 2025 nationwide koala estimate suggests extra koalas than beforehand estimated, with between 729,000 and 918,000. While that is excellent news, this will likely mirror elevated monitoring efforts (as talked about above) reasonably than a considerable inhabitants improve.  Koalas stay impacted by habitat loss, local weather change, automobile strikes and illness. 

The monitoring program is funded by the Federal Government, and the ultimate nationwide koala inhabitants estimates for Australia might be due in 2026. It is anticipated that future work may also assess inhabitants tendencies.

Dr McEvoy mentioned in relation to estimating koala numbers, researchers are utilizing a number of strategies to get the most effective information.

“There’s locations that have historical records of koalas but no one has seen one in quite some time, that’s when we will use a recorder,” he mentioned.

“If we confirm koalas are there, then we will come back and do a more detailed, more focused survey. You might put up the drone at that point and build in more methods as you go. It’s rarely a case that we will only use one method and they all have their advantages.”

And the benefit of acoustic recorders?

“They’re a pretty basic piece of kit, but they’re pretty powerful,” Dr McEvoy mentioned.