Australia's koalas could be wiped out within 30 years unless urgent action is taken to halt a decline in population, according to researchers.
They say development, climate change and bushfires have all combined to send the numbers of wild koalas plummeting.
The Australian Koala Foundation said a recent survey showed the population could have dropped by more than half in the past six years.
Many have been killed by the sexually transmitted disease chlamydia.
Previous estimates put the number of koalas at more than 100,000 - but the latest calculations suggest there could now be as few as 43,000.
The foundation collected field data from 1,800 sites and 80,000 trees to calculate the numbers.
In one area in northern Queensland estimated to have 20,000 koalas a decade ago, a team of eight people could not find a single animal in four days of searching.
The foundation said as well as problems caused by deforestation, hotter, drier conditions attributed to global warming had reduced the nutritional value of their staple food, eucalyptus leaves, leading to malnutrition.
Koalas, which are confined to forests in Australia's east and south, are notoriously fussy about what types of the leaves they eat.
Foundation chief Deborah Tabart said: "The koalas are missing everywhere we look. It's really no tree, no me. If you keep cutting down trees you don't have any koalas."
She is hoping the new figures will persuade the government's Threatened Species Steering Committee (TSSC) to list the koala as threatened.
But committee chairman Bob Beeton said a decision was not likely until mid-2010 - and the koala's status as one of the country's favourite animals would not be a factor.
"There's a number of species which are charismatic and emotionally charged. We don't consider that," Mr Beeton was reported as saying by the AFP agency.
"We'd consider the koala with the same level of diligence and dedication as if it were the death adder."