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Study solves longtime mystery of how a koala gets its drinking water

Reuters, May 12, 2020 9:00AM Kids News

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A wild koala licking a tree after rain. Picture: AAP/The University of Sydney media_cameraA wild koala licking a tree after rain. Picture: AAP/The University of Sydney

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Scientists have solved a mystery about koala behaviour: how these tree-dwelling* marsupials* drink enough water to live.

A new study describes koala drinking behaviour in the wild for the first time, finding that they lick water running down the smooth surface of tree trunks during rainfall — called stemflow — and do not only rely on the water content of the leaves that make up their diet.

The findings, which the researchers said could help in koala conservation* efforts, were based on 46 observations of koalas in the wild from 2006 to 2019, mostly at You Yangs Regional Park, west of Melbourne, Victoria.

media_cameraOne of the wild koalas the scientists watched licking a smooth tree trunk during rain. Picture: AAP/The University of Sydney

“I think the main message is that behavioural* observations in the wild are very important to establish what is normal and what is unusual, and to truly understand what animals need. If we watch them carefully, they will tell us,” said University of Sydney ethologist* Valentina Mella, lead author of the research published last week in the journal Ethology.

Koalas spend most of their lives high up in eucalyptus trees. They rely on a diet of eucalyptus leaves, normally eating around 500g to 800g daily.

media_cameraBecause koalas are nocturnal, it’s difficult to observe them drinking in this way. Picture: AAP/The University of Sydney

The word koala is thought to have come from the indigenous Dharug people’s word meaning “no water”.

The question of whether or how they drink water has long puzzled people.

“Koalas have been alleged* to never drink free water in the wild, or to drink only occasionally. Drinking behaviour has often been considered unusual and attributed to* disease or to severe heat stress,” Mella said.

koala drink media_cameraA koala in Belair National Park, SA, drinks rain off the road as desperately needed rain falls in South Australia in January. Picture: Brad Fleet

“Koalas were thought to gain the majority of the water that they require from the moisture content in the leaves that they feed on and to drink water unintentionally* in the wild by eating wet leaves after rain, or when dew is present on the leaf surface,” Mella added.

They sleep about 20 hours a day to conserve* energy because the leaves they eat require a lot of energy to digest.

“Koalas are nocturnal animals, so they are only active at night, and they are arboreal, which means that they live in trees and rely on them for food, shelter and, as we just discovered, also for drinking,” Mella said.

“Koalas actually spend 98 per cent of their lives in trees and the only time they are on the ground is when they are trying to find another tree with a more generous food supply or a mate.”

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KOALA NAMES
Scientific name: Phascolarctos cinereus

The scientific name comes from the Greek words phaskolos meaning pouched, arktos meaning bear, plus cinereus from the Latin* word meaning ashy-grey.

The name koala is thought to be a version of the Dharug people’s word meaning “no water”. The Dharug’s traditional lands span the area from Parramatta to the Blue Mountains of NSW. In South East Queensland, koalas are called dumbirrbi in the Jagera language, marrambi in the Yugarabul language, borobi in the Ugambeh language, and dumbribbi in the Turrbul language.

Source: Department of Environment and Science, Queensland

GLOSSARY

  • dwelling: home, house, place where you live
  • marsupials: group of mammals living in Australia and some in South America. Australian marsupials also include wombats, possums and kangaroos
  • conservation: the act of looking after something for the future
  • behavioural: to do with the behaviour of something
  • ethologist: science of animal behaviour
  • alleged: claimed, believed to be true
  • attributed to: acknowledged that a certain person did or said that thing
  • unintentionally: without meaning to
  • conserve: look after and keep for the future
  • Latin: language of Ancient Rome

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QUICK QUIZ

  1. What surprising thing did this research find?
  2. What do koalas eat and how much do they eat?
  3. Do animals sleep at night or in the day?
  4. Where do koalas spend 98 per cent of their time?
  5. What does the word koala mean in Dharug?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Koala Fact File
Draw an A4 picture of a eucalyptus tree with a koala in it or beside it and complete a fact file on koalas. Include all the information from the Kids News article with a diagram explaining what they eat and drink and how they live. Also include other names for koalas from the different indigenous languages.

Time: allow 25 minutes to complete this activity
Curriculum Links: English, Science

2. Extension
In 2009, after the Black Saturday bushfires in Victoria, a photo was shown around the world of volunteer firefighter David Tree sharing a bottle of water with a koala he called Sam. How does Sam’s drink of water compare to how we now know koalas drink in normal circumstances? Why would Sam have accepted a drink of water from David? What health problems could Sam have been suffering at the time? Share your thoughts on how drought, extreme heat or bushfires could impact koalas’ health. What could people do to help koalas in these situations?

Time: allow 10 minutes to complete this activity
Curriculum Links: English, Critical and creative thinking

VCOP ACTIVITY
Aside from this, there is also this!
Brackets are a great literacy tool for adding aside comments, or comments that could be covered over and the sentence still makes sense. What’s inside the brackets is extra information.

They can be used for a variety of effects: to add more detail, to add humour, to connect with the reader etc.

“My little brother, (the funniest kid I know) got himself into big trouble today.”

HAVE YOUR SAY: What Australian animal would you like to be an expert on?
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