What will koalas have for us to love them so much? Maybe her friendly and good-natured face, her learned ways. Whatever it was, they still have secrets for us. For example, it was not known how they had access to water in the tree tops. Do they absorb the moisture from the eucalyptus leaves they eat? Do they go dry to drink from the wells? Nobody really knew. A study published by researchers in the journal "Ethology" changes this. They say they know why koalas lick trees: because they extract moisture there.
The team is led by the University of Sydney. "For a long time, we thought that koalas didn't have to drink much because they got the leaves that they feed on," explains Valentina Mella. She is the author of the research. "But now we've seen them lick the water from the tree trunks. This explains how koalas get water in the wild, and that's very exciting. "
Adapted to Australia
These marsupials use the trees for their primary needs. Eat, refuge and rest. This study shows that they also need it for hydration.
Wild koalas eat about 510 grams of eucalyptus leaves every day. It is believed that the water in the foliage that they feed on contributes to their water consumption in summer and winter. Adapted to the Australian climate, koalas also have exceptional urine concentration skills. They limit the loss of breath and skin water compared to mammals of similar size.
In captivity, koalas have been observed to drink water. This behavior was often considered unusual and is attributed to illness or intense heat stress. Spot reports indicate that koalas in the wild drink from water fountains in summer when it is extremely hot. Sometimes koalas come close to get access to free water (in bottles, gardens, pools). However, this is considered an unusual fact.
Drink from the trees
Mella has compiled observations of koalas drinking in the wild between 2006 and 2019 in You Yangs Regional Park in Victoria. Forty-four observations of koalas licking the water that ran over the trunk of a tree during or immediately after the rain were recorded.
The other two observations were recorded between the cities of Gunnedah and Mullaley in the Liverpool Plain. One was an adult woman who drank for 15 minutes. The other was an adult man who drank at a constant pace for 34 minutes.
"Koalas are nocturnal animals and their behavior is rarely observed in heavy rain. It is likely that their drinking behavior has gone unnoticed," says the researcher.
It has been observed that koalas drank from branches and trunks when it rained in various weather conditions. Even if there was free water in the dams. "This indicates that the koalas were not drinking due to heat stress. This behavior probably represents how they naturally access the water," says Mella. In other words, koalas depend much more on the landscape than previously thought. "Koalas can be seriously harmful if lack of rain impairs access to free water." A new reason to preserve their living space. When we ask why koalas lick trees, we may ask: because they still can.