Unprecedented footage shows koalas slurping water from wet tree trunks both during and after rainstorms. The discovery solves a long-standing mystery about these adorable marsupials and how they’re able to stay hydrated.
A typical koala will eat around 150 grams (5.3 ounces) of eucalyptus leaves each day, providing them with an abundant but not completely sufficient source of water. As new evidence published in Ethology shows, koalas can access an alternative source of water without having to leave the cozy confines of their arboreal environment. They’re able to drink by lapping rainwater from wet tree trunks and branches.
“This significantly alters our understanding of how koalas gain water in the wild,” said Valentina Mella, the lead author of the new study and a researcher from the University of Sydney, in a press release. “It is very exciting.”
A video of a koala drinking from a tree trunk is below—and trust me, it’s worth viewing with sound on.
How these marsupials get their water, aside from eucalyptus leaves, has been somewhat of a mystery. Sure, koalas have a unique ability to retain water, but juicy eucalyptus leaves account for only around 75 percent of their total water intake during summer and winter, according to the new research.
Some koalas have been seen drinking from water holes when the weather gets really hot, but such accounts are strictly anecdotal. In rare situations, like after wildfires, desperate koalas will wander into urban settings, slurping water from bottles, gardens, and swimming pools. Captive koalas will drink water when it’s offered to them, but that’s typically only when they’re sick or heat stressed. Sourcing water outside of trees, therefore, doesn’t seem like typical koala behavior.
The new paper documents 46 examples of wild koalas licking rainfall from wet trees, pointing an alternative regular source of hydration for these animals.
Data for the new study was collected from 2006 to 2019 by independent ecologists and citizen sciences at Australia’s You Yangs Regional Park in Victoria and Liverpool Plains in New South Wales. These researchers made observations between dawn and dusk, and the slurping sessions were documented either during or immediately after rainstorms. Of the 46 examples, 44 were in You Yangs and two in Liverpool plains.
In one example, an adult female drank for 15 straight minutes while her joey rested contentedly on her lap. In another case, a male drank at a steady pace of around two licks per second for 34 straight minutes. Actually, it was probably longer than that, because the observers decided to move on. The lengthy sessions were probably due to low water-to-lick ratio, the researchers speculate.
The koalas were choosy about their slurping spots, preferring smooth bark, as water “can easily be obtained through licking as it runs down the trunk,” wrote the authors. Koalas were seen drinking in this way each time an observation was done in the rain, but because these sightings happened only during the day, this likely represents the tip of the iceberg.
“As koalas are nocturnal animals and observation of their behaviour rarely occurs during heavy rainfall, it is likely that their drinking behaviour has gone largely unnoticed and has therefore been underestimated in the past,” said Mella. “Our observations probably only represent a minority of the drinking that normally takes place in trees during rainfall.”
Interestingly, koalas licked wet trunks and branches across a wide range of weather conditions and even when free-standing water was available at nearby reservoirs.
“This suggests koalas were drinking not as a result of heat stress and that this behaviour is likely to represent how koalas naturally access water,” said Mella.