Ballarat wildlife rescuer, Jessica Robertson, said roaming pet cats were responsible for significant numbers of native animals being killed across the city.

"We are all volunteers so we are going out and rescuing animals that are being attacked by people's companion animals," Ms Robertson said. "At this time of year, spring, there are babies everywhere so they are prime targets."

One carer based in central Ballarat has a constant stream of orphaned and injured animals - including possums, birds and blue tongue lizards - which have been attacked by cats and brought to her by rescuers and members of the public each week.

Several weeks ago she had 18 possums in care.

Ms Robertson added that there was a real shortage of wildlife carers in Ballarat who could help to raise or rehabilitate these animals, explaining that it made it a "pretty critical" situation for volunteer carers.

She said very few possums and birds survived being attacked or bitten by a cat due to toxoplasmosis.

"Cats carry bacteria in their teeth and once they attack wildlife the toxins slowly poison the animal until it becomes paralysed and dies.

"If it's lucky, it will come straight into care or taken to a vet where it will get antibiotics. Unfortunately, many don't get found by people until they're sick on the ground and it's too late."

If there isn't a carer to nurse the animal back to health, it is more often than not euthanised by a vet.

While adding that carers love companion animals such as cats too, Ms Robertson said if people chose to have a pet they must do so responsibly.

"We want people to know the extent of wildlife injuries and deaths that come from cats because it is a problem that the community can solve by being responsible pet owners."

A book written by three of Australia's leading environmental scientists highlights the extent of the problem. Cats in Australia: Companion and killer is a compilation of key findings of hundreds of studies and management experience about cats across Australia, and it provides a staggering statistic.

It states that pet and feral cats contribute to killing more than two billion reptiles, birds and mammals each year in Australia.

Breaking that down, cats kill 3.1 million Australian mammals, 1.8 million reptiles and 1.3 million birds each day.

Last year, Professor Sarah Legge said Australia's mammal extinction rate was by far the highest in the world, with cats a leading cause of at least two-thirds of our mammal extinctions over the last 200 years.

Ballarat resident Michelle Imrei is the responsible owner of a pet cat named Bernie. Ms Imrei loves all animals but especially cats - which she described as quiet, intelligent and independent.

Explaining that they are each unique, she said that if a person decided to keep a cat as a pet then they needed to provide a safe environment for them and other animals - especially wildlife.

"As someone who has always shared a home with a cat or few, for most of fifty years, you become aware of their nature and needs," she said.

"Because we have domesticated our furry companions, it is our responsibility to provide the best care and also be aware of their instincts and how this affects the environment of other animals."

While independent and territorial, she said cats also required reassurance that they were safe and secure in their environment.

"By providing them with routine, regular feeds and fresh water every day, this helps them feel safe, and I find that they tend to not wander as much."

Ms Imrei said providing a pet cat with entertainment and encouraging regular exercise - with a climbing tower, toys or a secure area of garden with cat grass and mint - was also important to keep it stimulated.

For those without outdoor access, it is vital to keep the litterbox clean.

"My cat, Bernie, is lucky to have a diverse garden area and he is outside whenever we are home.

"He likes to sleep in the garden on a nice day," she said, adding there was plenty of shade for him and access to clean water.

When the family is not home, Bernie is contained inside the house and he is always kept indoors at night.

Allowing a cat to roam can not only be problematic for wildlife, but also increases the likelihood of them getting into fights with other cats and potentially spreading diseases.

"We keep him inside at night and when not at home, for his own safety, and also for the safety of other animals and wildlife."

Like many residents, Ms Imrei has issues with wandering neighbour cats venturing into her garden at night and killing native animals.

"Too many cats roam around and people really need to become aware of this and keep their cats inside at night, and also be aware of their nature during the day," she said.

Animal Justice Party MP Andy Meddick, a member for western Victoria, said people needed to be mindful that wildlife existed on this land long before humans brought domesticated cats and dogs into the country.

"We have a responsibility - both to the wildlife and to the domesticated animals - to keep them both safe," he said.

Responsible cat ownership also includes having your cat neutered so it does not contribute to an overbreeding problem. This step also prevents a cat from being a nuisance to neighbours while also reducing their inclination to roam.

Mr Meddick said cats could happily live their lives without being free to roam as long as they had opportunities to go outside for fresh air and exercise. To secure an outdoor area, a cat run or enclosure can be constructed.

While he is an advocate for cats being contained to their own properties, he is supportive of cat curfews too - initiatives that many local government areas are starting to put in place.

Somewhat of a contentious issue for some members of the community as it means cats are still able to roam during the day, he said curfews were a step in the right direction.

"If you are going to have a free roaming cat, then you should be responsible for keeping them in at night because there is an awful lot of our wildlife that are nocturnal and cats themselves are very efficient nocturnal predators," Mr Meddick said.

A cat curfew is in place in the City of Ballarat, meaning cat owners are required to keep their cats confined to their property between sunset and sunrise.

A spokesperson said that if council received concerns about a roaming cat at night, education was provided in the first instance: first a letter box drop in the area and then cat traps set up to trap the cat.

Once taken to the Ballarat Animal Shelter, education is provided to the cat owner and a first warning is issued.

"This has the most success to control first offences and we rarely see a repeat offender," they said.

A second offence results in an infringement of $165 and a notice to confine is issued. If council is notified of a third offence, then a further infringement for failing to comply with the notice is issued, costing the owner $500.

Pyrenees Shire also has a cat curfew.

Meanwhile, neighbouring Moorabool Shire recently conducted community consultation about a cat curfew as did Hepburn (it has not been implemented). Golden Plains Shire does not have a cat curfew either.

These surrounding councils report high levels of feral cats and have other initiatives in place, and can also supply cat traps to residents.