Koalas in danger

Eucalyptus leaves – which Australia's favourite marsupial depends on for survival – are being destroyed by abnormally high levels of greenhouse gases

A A A

The future of the koala, perhaps Australia's best-loved animal, is under threat because greenhouse gas emissions are making eucalyptus leaves – their sole food source – inedible.

Scientists warned yesterday that increased levels of carbon dioxide in the atmosphere were reducing nutrient levels in the leaves, and also boosting their toxic tannin content. That has serious implications for koalas and other marsupials that eat only, or mainly, the leaves of gum trees. These include a number of possum and wallaby species. "What we're seeing, essentially, is that the staple diet of these animals is being turned to leather," said Bill Foley, a science professor at the Australian National University (ANU) in Canberra. "This is potentially a very significant development for the future of some marsupial populations. Life is set to become extremely difficult for these animals."

Climate change could help to explain decreases in the numbers of brushtail possums and greater gliders (a large possum) in certain parts of Queensland where none of the usual factors – disease, hunting, loss of habitat – appears to be to blame. Jane De Gabriel, a zoologist at ANU, told The Australian newspaper that brushtail possums had been found to breed more prolifically in woodland areas where the protein levels in eucalyptus leaves were high. "This suggests that in areas where nutrient levels are inadequate, animals will not be able to reproduce successfully," she said. "What follows are extinctions of wildlife populations. It's pretty scary stuff."

Despite koalas' predilection for eucalyptus, the leaves are not nutritionally rich. In fact, even in the best conditions they are so low in protein that koalas – which spend up to 20 hours a day asleep, and most of the rest of their waking hours eating – have to eat 700g (1.5lb) of them a day to survive.

Like koalas, greater gliders feed only on eucalyptus leaves. Greater gliders have disappeared from some habitats where they were abundant 20 years ago. Brushtail possums, ringtail possums and many wallabies rely on the leaves as the major component of their diet. Ivan Lawler, a researcher at Queensland's James Cook University, found that when there was more carbon dioxide in the atmosphere, the levels of nitrogen and other nutrients fell.

"With more carbon dioxide, animals need to eat more and more leaves to get their required protein levels," he told The Australian. "The balance in the leaves shifts from nutrients to non-nutritional fibre. It eventually reaches a threshold when leaves are no longer tenable as a food source. The food chain for these animals is very finely balanced, and a small change can have serious consequences." WWF Australia warned recently that rising temperatures threatened numerous Australian native species, including the tree frog, the hare kangaroo, the tiny tree kangaroo and the greater bilby.

In a report last month, it said that such creatures – already endangered as a result of wide-scale land clearing and the introduction of exotic predators – could be pushed into extinction by climate change and its knock-on effects.

A dry life: On an ecological knife edge

Koalas live in coastal regions of eastern and southern Australia. Koala is an aboriginal word that means "doesn't drink". This is because koalas get more than 90 per cent of their water from eucalyptus leaves, which are toxic to most species. The only time they drink is when they fall ill or there is not enough moisture on leaves such as during droughts. Koalas can live as long as 17 years but the average male life expectancy is about 10 due to injuries from dogs and cars. The Australian Koala Foundation estimates that there are fewer than 100,000 koalas remaining in Australia today.

  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Photographer / Floorplanner / Domestic Energy Assessor

£16000 - £25000 per annum: Recruitment Genius: A Photographer/ Floor planner /...

Ashdown Group: Front-End Developer - Surrey - £40,000

£30000 - £40000 per annum: Ashdown Group: Front-End Developer - Guildford/Craw...

Recruitment Genius: Customer Service Assistant

£13500 - £15000 per annum: Recruitment Genius: A Customer Service Assistant is...

Recruitment Genius: Sales Executive - OTE £35,000

£16000 - £35000 per annum: Recruitment Genius: An ambitious and motivated Sale...

Day In a Page

Not even the 'putrid throat' could stop the Ross Poldark swoon-fest'

Not even the 'putrid throat' could stop the Ross Poldark swoon-fest'

How a costume drama became a Sunday night staple
Miliband promises no stamp duty for first-time buyers as he pushes Tories on housing

Miliband promises no stamp duty for first-time buyers

Labour leader pushes Tories on housing
Aviation history is littered with grand failures - from the the Bristol Brabazon to Concorde - but what went wrong with the SuperJumbo?

Aviation history is littered with grand failures

But what went wrong with the SuperJumbo?
Fear of Putin, Islamists and immigration is giving rise to a new generation of Soviet-style 'iron curtains' right across Europe

Fortress Europe?

Fear of Putin, Islamists and immigration is giving rise to a new generation of 'iron curtains'
Never mind what you're wearing, it's what you're reclining on

Never mind what you're wearing

It's what you're reclining on that matters
General Election 2015: Chuka Umunna on the benefits of immigration, humility – and his leader Ed Miliband

Chuka Umunna: A virus of racism runs through Ukip

The shadow business secretary on the benefits of immigration, humility – and his leader Ed Miliband
Yemen crisis: This exotic war will soon become Europe's problem

Yemen's exotic war will soon affect Europe

Terrorism and boatloads of desperate migrants will be the outcome of the Saudi air campaign, says Patrick Cockburn
Marginal Streets project aims to document voters in the run-up to the General Election

Marginal Streets project documents voters

Independent photographers Joseph Fox and Orlando Gili are uploading two portraits of constituents to their website for each day of the campaign
Game of Thrones: Visit the real-life kingdom of Westeros to see where violent history ends and telly tourism begins

The real-life kingdom of Westeros

Is there something a little uncomfortable about Game of Thrones shooting in Northern Ireland?
How to survive a social-media mauling, by the tough women of Twitter

How to survive a Twitter mauling

Mary Beard, Caroline Criado-Perez, Louise Mensch, Bunny La Roche and Courtney Barrasford reveal how to trounce the trolls
Gallipoli centenary: At dawn, the young remember the young who perished in one of the First World War's bloodiest battles

At dawn, the young remember the young

A century ago, soldiers of the Empire – many no more than boys – spilt on to Gallipoli’s beaches. On this 100th Anzac Day, there are personal, poetic tributes to their sacrifice
Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves

Follow the money as never before

Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves, reports Rupert Cornwell
Samuel West interview: The actor and director on austerity, unionisation, and not mentioning his famous parents

Samuel West interview

The actor and director on austerity, unionisation, and not mentioning his famous parents
General Election 2015: Imagine if the leading political parties were fashion labels

Imagine if the leading political parties were fashion labels

Fashion editor, Alexander Fury, on what the leaders' appearances tell us about them
Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

The architect of the HeForShe movement and head of UN Women on the world's failure to combat domestic violence