More species are being wiped from existence in Australia than almost anywhere else on the planet, with experts saying the nation's arid centre has undergone "arguably the greatest rate of mammal extinction in the world".

Key points: The Northern Territory has lost 17 mammal species, the NT Government says

The Northern Territory has lost 17 mammal species, the NT Government says Experts say Australia needs to dramatically increase funding to stop further species losses

Experts say Australia needs to dramatically increase funding to stop further species losses In recent times black rats have been found colonising parts of Kakadu National Park and Arnhem Land

Yet a 2016 report reveals Australians are spending far more money feeding their pet cats than on protecting the threatened species that remain.

Now experts fear if current conservation practices and resourcing is maintained, the country's extinction crisis will only get worse.

In the past 200 years, Australia has lost more mammal species than any other country, with 34 species now extinct.

According to the Northern Territory Government, 17 NT mammal species have been lost.

The Threatened Species Recovery Hub had slightly different figures that showed at least 20 mammal species were thought to be extinct from the NT, although some persisted elsewhere in the country or in enclosures.

Arid Lands Environment Centre policy officer Alex Read said Central Australia has experienced "arguably the greatest rate of mammal extinction in the world".

In the past 10 years, NT Department of Environment and Natural Resources executive director Dr Graeme Gillespie said the most prominent fauna declines nationally were among small to medium-sized mammals of northern Australia, but those in arid areas also remained under threat.

"The arid lands of central Australia have the worst record of mammal extinctions since European settlement," Dr Gillespie said.

"It is generally perceived that such declines happened 100 years ago and are no longer an issue. This is not the case."

The most recent update to the Red List of Threatened Species named Australia as the fourth-worst country for overall animal extinctions, behind the United States, French Polynesia and Mauritius.

There are almost 500 threatened fauna species across Australia — 101 of which are in the Northern Territory.

A senate committee is currently looking into ways to curtail Australia's faunal extinction crisis, and has received more than 200 submissions.

It is due to complete a report by December 4 this year.

'Death by a thousand cuts'

Australia's spending on preventing extinctions is low, the Threatened Species Recovery Hub said, particularly compared to other western nations and the size of its extinction problem.

It claimed that to match the spending of other western countries, Australia's investment would need to increase to $1.2-$1.5 billion a year.

Current government spending fell far short of that.

A Federal Department of Environment and Energy spokesperson said since appointing a Threatened Species Commissioner in 2014 it had "mobilised" more than $302 million on "supporting threatened species outcomes" — equating to about $75.5 million a year.

During the next five years, the spokesperson said threatened species projects were set to receive $135 million through the Regional Land Partnerships initiative.

In the Northern Territory, an environment department spokesperson said last financial year, the flora and fauna division was allocated a budget of $2.1 million to work on threatened species conservation.

In 2018-2019, the budget increased to $2.4 million.

Dr John Woinarski, from the Threatened Species Recovery Hub, said that additional funding was required in every part of the species recovery process.

This included controlling threats, monitoring populations of threatened species, surveys and basic research, captive-breeding and translocations, enhancing community involvement, better resourcing for administrative processes, and more effective communication about the issues.

He said aside from government, additional funding could also be sourced through NGOs and philanthropists.

"The amount of spending we consider is likely to be needed (about $1.5 billion per year across all threatened species) may seem a large call," he told the ABC.

"But as context Australians spend far more than that ($4 billion) every year on food and medicines for their pet cats."

Proponents were also critical of the key piece of legislation designed to protect Australia's fauna — the Environmental Protection and Biodiversity Conservation Act 1999.

Arid Lands Environment Centre policy officer Alex Read said it has "mostly failed in its fundamental purpose" and believed it facilitated development at the expense of the environment.

He said there needed to be an improved focus on preventing species loss, rather than simply minimising these losses, in order to address what he described as a "death by a thousand cuts".

He warned that without Federal Government support for "a renewed direction in threatened species conservation and protection" the observed rate of fauna extinctions will continue.

The Threatened Species Recovery Hub also said the legislation should provide a way for wildlife that was culturally significant to Aboriginal people and declining on country to be listed, even if it did not meet the thresholds for listing as threatened.

Yet the Federal Department of Environment and Energy said the EPBC Act provides a "significant foundation", upon which longer term conservation planning and action is directed.

However it noted that many of the species listed under the act do not have their status reviewed regularly, as this was challenging due to the large number listed.

It also said the Threatened Species Commissioner was working to implement the Threatened Species Strategy, which included targets to tackle feral cats and their impacts, improve the trajectory of 20 mammals, 20 birds and 30 plant species and improve recovery practices by 2020, among other things.

The Northern Territory is home to 101 threatened species — including bilbies. ( Department of Natural Resources )

'A convergence of pressures'

In recent times black rats, a species introduced from Europe, have been found colonising remote parts of Kakadu National Park and Arnhem Land, Dr Gillespie said.

He suspected this was due to the decline of small and medium-sized native mammals, resulting in vacant niches and a loss of competition.

Yet he said it was difficult to pinpoint what the impacts would be, or what caused the mammalian declines in the first place.

"Unlike some of the more historic declines … it has been a little bit less clear as to what's actually driving those [declines] and it appears to me the complex interaction of a combination of factors," he said.

A submission from the Federal Department of Environment and Energy made a similar point, saying understanding biodiversity declines across Australia was complicated as many species suffer from the "cumulative impacts of multiple pressures".

"For example, during the past five years, evidence has emerged that the greatest impact on mammals in northern Australia comes from a combination of predation by feral cats in recently burned environments," it said.

"In the absence of cats, native mammals are able to survive fire and continue to find food, while cats forage less effectively in unburned environments."

The NT Department of Environment and Natural Resources said the jurisdiction was in dire need of better monitoring programs.

"The Central Rock-rat program is an excellent, but possibly the only, example in the NT of an adequate threatened species monitoring and evaluation program in a proper targeted adaptive management framework," it stated.

"Often basic monitoring of distribution and abundance, and assessment of threats is what is most needed for NT threatened species."

Dr Woinarski said most mass extinctions globally were caused by direct human hunting and land clearing — but that was certainly not the case with the extinctions of Australian mammal fauna.

Instead he pointed to predation by cats, the introduction of livestock and rabbits, changed water sources and changed the fire regimes that followed the loss of Aboriginal fire management.

"And all those factors sort of work as an ugly cocktail that lead to losses of many mammal species," he said.