Scientists consider kangaroos 'worse than rabbits' while feral pigs are also in their sights

These destructive and highly mobile beasts are a problem across almost half the continent and cost farmers more than $100 million each year.

Farmers have long borne the burden of controlling the pigs, spending an estimated $47.7 million each year on the job.

A national strategy has been launched asking for public feedback on plans to better co-ordinate the fight.

It comes as another study was released this week, finding kangaroos are causing more overgrazing problems than rabbits.

Victoria's current kangaroo population is estimated at almost two million - up almost 40 per cent in two years leading to lift in culling in that state.

That study, by the UNSW, considers whether "population removal" may need to be considered within some public lands.

Authors of the draft National Feral Pig Action Plan say it is the first step in Australia's cohesive approach to feral pig management.

One new hope for farmers is the development of a new bait called HOGGONE which has received regulatory approval.

The bait is a Schedule 6 poison so landholders can buy and use it without specific training or certification, and is deployed via a specially designed bait box that non-target animals cannot access.

Feral pigs are not only a threat to agriculture but the environmental damage they do is immense.

John Maher, chair of the national feral pig strategy steering group, stressed the growing impact of the problem in Australia.

"Feral pigs are a major pest and risk to Australia's environment, and our $65 billion agricultural sector.

"They destroy land, crops and pastures, spread weeds and disease, prey on livestock, impact biodiversity and cause serious damage to our natural environment and cultural sites," Mr Maher said.

Feral pigs also pose a major biosecurity threat if there were disease outbreaks like foot and mouth disease or African swine fever.

Feral pigs have been partly blamed for the soil-borne fungal transmission of Panama disease which threatens Australia's banana industry.

The strategy says farmers need help.

"Coordinated actions by private and public land managers through well-managed programs are needed to protect assets and maintain suppression of feral pig populations," it says.

The draft plan wants to build a network of regional coordinators to work with community groups and land managers to tackle the problem.

It highlights a program in the western Riverina of New South Wales from 2016-2019 which tried to control pigs across 1.3 million hectares after farmers asked for help, not only on their farms, but on public land like national parks.

Aerial shoots claimed 34,519 feral pigs costing $1.37 million for the program.

It had been estimated that part of the Riverina would be home to about two million feral pigs within five years if their spread was not stopped.

"Suppression, or eradication, of feral pig populations is crucial, and sustained effort will be needed by land managers working together, informed by surveillance, monitoring and data, and using combinations of humane best practice management methods for their locality or region," Mr Maher said.

The draft plan can be found here with responses to: planfeedback@feralpigs.com.au by Friday, February 26.

Meanwhile, another study has been released highlighting the impact of kangaroos.

The joint study led by UNSW Sydney found conservation reserves are showing signs of kangaroo overgrazing and their impact "appeared to be more damaging to the land than rabbits".

Professor Michael Letnic said: "We tend to think of kangaroo grazing as a natural process because they're a native species, but there are now too many kangaroos in conservation reserves. Their grazing can be detrimental for biodiversity conservation."

Overgrazing by one native species is having an impact on other native species, like the critically endangered Plains Wanderer of which there are less than 1000 left in the wild.

"Rabbits and other introduced herbivores like goats are often considered the main contributor to overgrazing in Australia," said the study's lead author Dr Charlotte Mills.

"But we found kangaroos had a greater impact on the land - and on the grass in particular."

Professor Letnic says while kangaroos on farms have been managed for 100 years, they have generally been unmanaged on conservation reserves.

"This research changes thinking by suggesting it's time to ask some questions," he said.

"We need to ask whether there are too many kangaroos and if they're having unacceptable impacts on our conservation reserves."