Gaby
Koalas (Phascolarctos cinereus) typically descend from trees to the ground for about 10 minutes at a time, but this brief period is linked to two-thirds of their recorded deaths. This alarming statistic comes from a new study conducted by researchers at the University of Queensland and the University of the Sunshine Coast in Australia.
Over the past three decades, the population of these cartoonish marsupials native to Australia has plummeted by 54 percent.
Millions of dollars are spent each year to protect koalas, with a strong focus on environmental conservation and animal rehabilitation. Yet, despite the significant efforts of animal welfare advocates, most koala deaths occur during their time on the ground—primarily due to vehicle collisions and dog attacks.
Traditional GPS tracking provides limited insight into these movements, as animals are typically monitored only once or twice a day.
“Koalas primarily live in trees, but due to extensive deforestation, they increasingly have to move on the ground, putting them at serious risk of injury and death,” said Gabriella Sparks, a graduate student at the University of Queensland and the lead author of the study.
How Was the Study Conducted?
Gabriella and her colleagues aimed to gain a better understanding of what koalas do during these ground movements.
“We didn’t 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, and what influences these decisions. These are significant gaps in our knowledge,” the researcher explained.
To fill these gaps, the researchers used accelerometers—biologgers that capture three-dimensional movement at hundreds of points per second. This technology allowed scientists to determine the orientation and movement of koalas during specific ground excursions, as reported by Sci.news.
Over the course of eight days, the team observed 10 koalas in the wild, outfitting them with collars equipped with accelerometers and high-resolution GPS devices. The researchers found that koalas descended to the ground two to three times a day, spending an average of 10 minutes each time.
During a single ground visit, koalas covered an average distance of 260 meters, primarily moving at a speed of 1.7 km/h, but occasionally hopping at speeds of up to 10.4 km/h.
By combining accelerometer and GPS data, the scientists identified specific trees between which the koalas were moving.
“This gave us an incredibly detailed insight into how koalas navigate their environment. As the study confirmed, koalas spend most of their time in trees, sleeping and eating there, but the true extent of their attachment to trees was shocking,” Sparks noted.
The researchers were surprised by how rarely and briefly koalas are on the ground: 10 minutes accounts for less than one percent of their daily time. The animals spent nearly as many minutes sitting as they did walking, and only about 7 percent of their time was spent hopping.
The team speculated that this might indicate koalas are carefully assessing their surroundings while on the move, perhaps evaluating trees before selecting the best one. Alternatively, it could relate to the energy expenditure involved in hopping.
This study is the first to document the brief ground movements of wild koalas and raises new questions about their mobility in increasingly shrinking habitats.
With the data collected, scientists have gained a clearer understanding of koala behavior. In the future, this will help researchers develop more effective environmental management strategies and reduce the risk of fatalities in critical areas. “This study is just one piece of the puzzle, but it sheds new light on how koalas interact with an environment that is constantly changing due to human impact,” Sparks said.
This month, the researchers presented their findings at the annual conference of the Society for Experimental Biology in Antwerp, Belgium.
