VOA慢速英语2020--研究发现考拉是如何喝水的

Scientists have long wondered how Australia's koalas get enough water to live. A new study provides an answer.

In the wild, koalas get water from the plant leaves they eat. But they also get it from water running down the side of tree trunks during rainfall -- what we might call "tree-licking." Scientists have a term for this process -- "stemflow."

The lead author of the new report on koalas is Valentina Mella of the University of Sydney. It was earlier thought, she explains, that the animals got most of their water from moisture in the leaves they ate.

Mella and other researchers based their findings on 46 observations of koalas in the wild from 2006 to 2019. Most of the animals were observed at You Yangs Regional Park in the Australian state of Victoria.

Mella notes that koalas are largely nocturnal animals. This means they are active at night.

"They are arboreal¹," adds Mella. This means they live in trees and rely on them for food, shelter and, as the researchers just discovered, also for drinking.

Koalas spend most of their lives high up in eucalyptus² trees. They eat large amount of eucalyptus leaves. An adult koala normally eats between 500 to 800 grams of leaves a day.

Because of their diet, koalas sleep a lot -- about 20 hours a day. Their diet of tree leaves requires much energy to digest.

Mella notes that "koalas actually spend 98% of their lives in trees." She adds that the only time they come down to the ground is to find another tree with better food supplies or a mate.

In fact, the word "koala" is said to have come from an Aboriginal³ word meaning ‘no drink.' Koalas did not go down onto the ground very often. So, it was thought that they had no need to drink water.

The researchers published their findings in the journal Ethology. They said the study may be useful in efforts to protect koalas for future generations.

Mella says that the "observations in the wild are very important." She adds that they can help to establish what is normal and what is not.

"If we watch them carefully," she says, "they will tell us."

Koalas have been under threat due to a loss of their natural habitat. Australia's environment minister told the Australian Broadcasting Corporation that recent wildfires have destroyed "up to 30% of their habitat."

I'm Anna Matteo.

Words in This Story

leaf – n. one of the flat and typically green parts of a plant that grow from a stem or twig⁴

lick – v. to draw the tongue over

moisture – n. a small amount of a liquid (such as water) that makes something wet or moist

nocturnal – adj. active at night

arboreal – adj. living in or often found in trees

digest – v. to change or become changed into simpler forms that can be used by the body

habitat – n. the place or environment where a plant or animal naturally or normally lives and grows

1 arboreal   

adj.树栖的；树的

参考例句：

• Man was evolved from an ancestor that was probably arboreal.人大概是从住在树上的祖先进化而来的。
• Koala is an arboreal Australian marsupial.考拉是一种澳大利亚树栖有袋动物。

2 eucalyptus   

n.桉树，桉属植物

参考例句：

• Eucalyptus oil is good for easing muscular aches and pains.桉树油可以很好地缓解肌肉的疼痛。
• The birds rustled in the eucalyptus trees.鸟在桉树弄出沙沙的响声。

3 aboriginal   

adj.（指动植物）土生的，原产地的，土著的

参考例句：

• They managed to wipe out the entire aboriginal population.他们终于把那些土著人全部消灭了。
• The lndians are the aboriginal Americans.印第安人是美国的土著人。

4 twig   

n.小树枝，嫩枝；v.理解

参考例句：

• He heard the sharp crack of a twig.他听到树枝清脆的断裂声。
• The sharp sound of a twig snapping scared the badger away.细枝突然折断的刺耳声把獾惊跑了。