Koalas (Phascolarctos cinereus) spend around 10 min per day on the ground, but this ground-time is associated with two-thirds of recorded koala deaths, according to new research by scientists from the University of Queensland and the University of the Sunshine Coast.
Koala in the wild with a custom-built collar containing a GPS logger and accelerometer. Image credit: Ami Fadhillah Amir Abdul Nasir.
Koala populations in Australia have declined by 54% in the last three decades.
Millions of dollars are spent annually on protecting koalas, focusing on safeguarding habitat and treating disease.
Yet, two thirds of all koala deaths occur when they are moving along the ground, due to vehicle strikes and dog attacks.
Despite decades of research, little is known about how koalas move on the ground.
Traditional GPS tracking provides limited insight into these movements, as they generally record locations only once or twice a day.
“Koalas are mostly tree-dwelling, but due to extensive land clearing, they’re increasingly forced to travel on the ground, which puts them at serious risk of injury and death,” said Gabriella Sparkes, a Ph.D. student at the University of Queensland.
“I wanted to better understand what koalas do during these ground movements.”
“We don’t yet have a clear understanding of how often koalas come down from trees, how far or fast they move, how long they stay on the ground, or what influences those decisions.”
“These are critical knowledge gaps if we want to identify high-risk areas or times and develop strategies to reduce threats during these vulnerable moments.”
To address these gaps, the researchers used accelerometers — bio-loggers that record three-dimensional movement at hundreds of points per second — to determine the orientation and movement of koalas during specific behaviors.
They collared 10 koalas in the wild with accelerometers and high-resolution GPS devices for an average of 8 days.
They found that koalas visited the ground three times per day on average, totaling only 45 minutes.
Koalas traveled on average 260 m per ground visit, mainly walking at 1.7 km/h with occasional bounding at 10.4 km/h.
Combining accelerometer and GPS data, they identified the specific trees koalas moved between.
“When paired with GPS tracks, this gives us an incredibly detailed view of how koalas move through their habitat,” Sparkes said.
“This research has revealed that, unsurprisingly, koalas spend most of their time in trees, sleeping and feeding — but the true scale of their tree-hugging was shocking.”
“What surprised us was how infrequently and briefly they use the ground — just 2-3 times per night, averaging around 10 minutes in total, or less than 1% of their day.”
“They spent nearly as much time sitting and pausing as they did walking, and only about 7% of their time on the ground was spent bounding.”
“This may indicate that koalas are carefully assessing their environment as they move, possibly evaluating trees before selecting one to climb, or it may reflect the energetic costs of bounding.”
This study is the first to document these fine-scale ground movements in wild koalas, and it opens new questions about how they navigate increasingly fragmented habitats.
“We’re now looking at environmental features that influence how long koalas stay in trees,” Sparkes said.
“If we can identify the kinds of trees or habitat conditions that encourage koalas to remain in trees for longer, we may be able to design or manage landscapes in ways that reduce the need for ground travel.”
Based on these findings, the team hopes to influence the direction of koala conservation efforts, which could include prioritizing certain vegetation types, improving canopy connectivity, or reducing gaps between safe trees — all of which could help keep koalas off the ground and out of the danger zone.
The findings help to provide a much clearer picture of koala behavior, which can help to guide more effective habitat management and reduce the risk of fatalities in critical areas.
“This research is just one piece of the puzzle, but it adds an important layer to our understanding of how koalas interact with increasingly human-altered environments,” Sparkes said.
The scientists presented their results on July 1, 2025 at the Society for Experimental Biology Annual Conference in Antwerp, Belgium.
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Gabriella R. Sparkes et al. Monitoring the ‘Mundane’: What Do Koalas Do When They’re Not Sleeping? SEB 2025, abstract # A16.1
