There's no doubt koalas are on the move away from Gunnedah and that the horrendous heat of last summer and lack of water played a major part.

This spells bad news for the self-proclaimed Koala Capital of the World.

The report shows that feral cats are the main reason for mammal extinction in Australia climate change ranked fifth, while habitat loss ranked fourth.

One of the report's authors, Professor John Woinarski, said that while feral cats were not a problem for koalas, other factors were.

"It is for many other species but not for koalas," Professor Woinarski said.

"The impact of these different threats varies across different parts of Australia."

He said it was more likely climate change, disease such as chlamydia and dog attacks were the cause of declining koala numbers.

"Climate change and clearing are major problems much of their habitat has been cleared," he said.

"Climate change is likely to increase the number of hot days in (Gunnedah and) koalas don't like really hot days."

The extensive report, called The Action Plan for Australian Mammals 2012, collated information covering 300 species including bandicoots, wombats, quolls, rodents and platypuses.

Professor Woinarski, of the Research Institute of Environment and Livelihoods at Darwin University, said statistics were collated up to the end of 2012.

It took two years for him and his co-authors Andrew Burbidge and Peter Harrison to sift through it before the 1000-page report was released through CSIRO Publishing.

The action plan concluded that 29 Australian mammal species had become extinct and 63 species required urgent conservation action.

It was the first review to assess the conservation status of all Australian mammals. The koala's conservation status is vulnerable and the new report shows there is "a very severe reduction, more than 80 per cent, in some inland sub-populations".

"The overall rate of decline in population size over the last 18 to 24 years (which equals three generations) was estimated at about 28 per cent by the Threatened Species Scientific Committee, with this rate substantially influenced by a severe decline in inland regions most exposed to recent drought," the report said.

"Climate change is expected to lead to an increased rate of population reduction over the next 20 to 30 years and the impacts of other threats will magnify over this period."

Re-sampling in 2011 of 45 transects in the Pilliga Forest, originally sampled in 1993 and 1994, noted a more-than-75 per cent reduction in detection rates.