Farmers and environmentalists in northern Tasmania are teaming up to eradicate feral cats blamed for killing more than 20 billion native Australian animals a year, as well as threatening livestock.

The "effective" eradication of feral cats has been named a priority by Environment Minister Greg Hunt, under a new 10-year plan.

But feral cats are not only wiping out native wildlife populations. Farmers report the cats are also killing their livestock.

Tasmanian sheep farmer Bruce Young says the diseases the feral cats carry are having devastating consequences.

Mr Young has raised lambs on his property for 40 years.

But now the parasite toxoplasmosis, spread by feral cats, means he is losing many of those lambs before they are born.

"We had a lot of ewes abort from about middle pregnancy up until lambing around August 10," he said.

"This year we think we are back 500 lambs due to toxoplasmosis and 500 lambs at $120 [each] is not difficult to work out.

"So that's the sort of income you can lose, and there are others around that have lost similar amounts of lambs.

"It's just another impost, but most of all it's the devastation to our fauna and our marsupials, ground-nesting birds, these are the things that are really under pressure.

"I don't think there is any doubt that environmentally the cat is an enormously destructive animal. I mean they are a beautiful pet, but they are a very destructive animal."

Feral cats spread fatal disease

Announcing his plan to eradicate feral cats, Mr Hunt said "there are up to 20 million feral cats taking up to four native Australian animals a night".

"That's over 20 billion Australian native species being destroyed a year," he said.

Chris Johnson, Professor of Wildlife at University of Tasmania, said toxoplasmosis was present in 80 to 90 per cent of the state's feral cat population - one of the highest rates of the disease in the world.

"It's partly climate, the toxoplasmosis organism likes cool, moist climates, and the abundance of cats can be quite high in farmland. So probably there is lots of cycling of parasites between cat populations and native species and introduced rodents as well," Professor Johnson said.

"The way it works is that the parasite reproduces in cats and its eggs then gets spread in the cat faeces. They can be ingested by herbivores like bandicoots and native mice but also sheep."

Toxoplasmosis not only causes sheep to abort, but can cause changes in behaviour in some infected animals.

"The toxoplasmosis organism gets into the body and forms cysts and some of those cysts form in the brain," Professor Johnson said.

"And in rodents at least they can change behaviour. They have this specific effect on behaviour which is to make the mouse less frightened of cats and the reason that the organism does that to the mouse is that it actually wants the mouse to be eaten by a cat, because the parasite then completes its life cycle and reproduces again."

Controlling cats best option to saving livestock

Tasmania's chief veterinary officer Rod Andrewartha said controlling cats, both feral and domestic, appeared to be the only answer for farmers.

"You can try and take some precautions for it as far as the sheep are concerned, try and keep your cats out of your grain stores, try and preventing the cats from contaminating your hay, your grain and things you are going to feed to your sheep, that's about all you can do with that," he said.

These animals pose a disease threat as well as a predatory threat. Environment Minister Greg Hunt.

In the quest to rid their farms of feral cats, farmers in Tasmania have discovered an unexpected ally in Mr Hunt.

"These animals pose a disease threat as well as a predatory threat and the solution is the same in each part. We simply have to work to thin and then to effectively eradicate the problem of feral cats," Mr Hunt said.

And despite budget cuts to Landcare earlier this year, new money has been promised to help community groups trap and eradicate feral cats.

In northern Tasmania, Landcare groups have already seized the initiative to try to catch and destroy feral cats.

Kevin Knowles, from the Upper Meander Catchment Landcare Group, has begun setting traps.

"There seemed to be an explosion of them anecdotally, so we purchased half a dozen traps and started mucking about with them, and realised there is hell of a lot of cats out there," Mr Knowles said.

"Generally speaking, the information we can gather is that across Australia there is one cat per square kilometre.

"But we are getting five or six cats per square kilometre. That's a huge change."

Jamie Cooper from Feral Cat Management Solutions said traps had caught dozens of cats.

"We are removing a lot of cats from the environment, we've actually undertaken quite a few community programs and they have been really quite successful," Mr Cooper said.

New plan to use Tasmanian devils to fight cats

In Tasmania, there is one animal that until recently kept feral cats at bay - the Tasmanian devil.

The species now survives only in Tasmania, but the devil's existence has been further threatened by the spread of a communicable facial cancer.

Trowunna Wildlife Park director Androo Kelly said the natural predator had a key role in limiting the spread of the cats.

I don't expect that [Tasmanian] devils will eradicate cats but they might limit... them and they might reduce their impact. Professor Chris Johnson, Professor of Wildlife at University of Tasmania

"Tasmanian devils will find kittens ... and will destroy the kittens," Mr Kelly said.

Now there are calls to reintroduce the devils into controlled areas across Australia.

The Victorian Government is considering releasing the Tasmanian devils into Wilson's Promontory National Park in a bid to restore an ecological balance between feral cats and wildlife.

Professor Johnson says there is merit to this plan.

"I don't expect that devils will eradicate cats but they might keep the lid on them and they might reduce their impact," he said.

"The idea of introducing devils to parts of mainland Australia sounds outlandish but it's actually quite sensible, because devils used to be widespread on the mainland until fairly recently."

Mr Kelly warned that using a native predator to control an imported predator sounded appealing, but said caution was needed, a view backed by Mr Hunt.

"I wouldn't want to take a risk with unintended consequences," the Environment Minister said.

"So let's stabilise the population in Tasmania, and have the scientists research whether it is good for the Tassie devil and good for the broader native Australian population with regards to native birds, native mammals on the mainland."