The responsibility for choosing which Australian native species survive – and which go extinct – may ultimately fall to ordinary Australians.

The dilemma over how much of Australia we will pass on to our grandchildren cannot be solved by science – but only by society, one of the nation's leading ecologists, Professor Hugh Possingham, warned today.

Prof Possingham, who is director of the ARC Centre of Excellence for Environmental Decisions (CEED) at The University of Queensland, said that world-first Australian research was showing that it was now possible to estimate how many can be saved based on how much was spent on protecting them and their habitats.

“For the first time ever, we are starting to get a handle on the return on investment from conservation,” he said.

“However, this also clearly shows that, at current levels of funding and current rates of extinction, we won't be able to save everything.

“Then it will come down to a public decision about what kind of Australia we really want, which native species we should strive to keep – and how many we feel we can afford to let go.”

Groundbreaking research by Dr Michael McCarthy and colleagues at Melbourne University had shown that an annual national investment of just $10m a year could reduce the number of threatened Australian bird species from around 270 to 230 over 80 years, he said. Even then a few species would be lost.

“This is the first clear evidence, probably worldwide, how much it costs to save species. However the amount of $10m is roughly three times what we currently spend nationally on bird conservation.

“It seems like a trivial amount to secure Australia's avifauna which is currently disappearing at about 100 times the ‘background rate'.

Basically it comes down to a decision whether we lose a bird a decade – or a bird every century.”

In a situation where environmental funding remains tight it will be necessary for Australians to take hard decisions, Professor Possingham said.

“For example, are we wasting scarce money trying to save some species from extinction?

"Should we instead put more effort into saving those with better prospects of survival?

“These are not questions that science can answer: they come down to our values as a society.”

In another groundbreaking CEED study, Dr Josie Carwardine, Dr Tara Martin and colleagues estimated it would cost the nation $40 million a year to protect 45 mammals, birds and reptiles from extinction in the Kimberley.

“We now know what it will cost to protect Australia's last region with an intact native fauna," Professor Possingham said.

"The question we must decide is whether we are willing to make the necessary investment.”

Even more difficult for the public were decisions about protecting things like unique native grasslands and the obscure plants and insects they harboured.

“When people see these, do they realise it is a complex and unique Australian ecosystem – or do they just see grass?” he said.

With such problematical decisions ahead of them, Australians urgently needed to learn a lot more about their native land – and the rare animals and plants that inhabited it, Professor Possingham said.

“I take people on bird walks through the suburbs of Brisbane – and they are astonished to see or hear as many as 70 species of native birds in two hours.

We all need to open our eyes more to the wonderful Australia that surround us.

"Europeans and Americans are amazed to see the wildlife that we take for granted.”