Koalas spend only 1% of their life on the ground – but it’s killing them

(Press-News.org) Koalas are a nationally endangered and iconic species in Australia, yet their populations are rapidly declining due to habitat loss, fragmentation, and disease, and very little is known about the fine-scale movements of koalas – especially when they’re on the ground. New research reveals that koalas only spend around 10 minutes per day on the ground, but this ground-time is associated with two-thirds of recorded koala deaths.

“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,” says Gabriella Sparkes, a PhD student at the university of Queensland, Australia. “I wanted to better understand what koalas do during these ground movements.”

Previous research has shown that around 66% of all koala deaths occur while they’re on the ground, mostly due to dog attacks and vehicle strikes, yet surprisingly little is known about their ground-based behaviour. “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,” says Ms Sparkes. “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 analyse koala movement, Ms Sparkes and her team fitted wild koalas with collars containing GPS loggers and six-axis accelerometers in a landscape that has largely been cleared for farming. Their locations were recorded every five minutes, which increased to five-second bursts during ground travel.

The accelerometers allowed Ms Sparkes to identify distinct types of movement, such as walking, climbing and sitting, and this helped her to classify both tree-based and ground-based behaviour patterns on a fine-scale. “When paired with GPS tracks, this gives us an incredibly detailed view of how koalas move through their habitat,” says Ms Sparkes.

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,” says Ms Sparkes.

They also found that koalas on the ground move with very little urgency. “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,” says Ms Sparkes. “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,” says Ms Sparkes. “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, Ms Sparkes and her team hope to influence the direction of koala conservation efforts, which could include prioritising 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.

These findings help to provide a much clearer picture of koala behaviour, 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,” says Ms Sparkes.

This research is being presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium on the 9th July 2025.

END