Hayley reports on the koala problem
There could be no more koalas left in the wild in 30 years, unless something is done to stop their decline, according to experts.
The Australian Koala Foundation said a survey shows the population could have halved in the last six years, falling from 100,000 to 43,000.
It's thought climate change, building work, bushfires and diseases have sent koala numbers plummeting.
The group want to get the koala officially listed as endangered.
If an animal is listed as endangered, it gets special protection, which the researchers think the koalas need.
The foundation collected information from 1,800 sites and 80,000 trees to calculate the numbers.
Koala mainly eat eucalyptus tree leaves
A baby koala is called a joey
Koalas weigh between 5kg and 14kg
One area in northern Queensland had about 20,000 koalas 10 years ago.
But a team of eight people could not find a single animal in four days of searching.
The foundation says koalas are vulnerable because they only eat a few type of leaves.
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."