Cats were brought to Tasmania as domestic animals by early European explorers and settlers. Some of these cats escaped or were abandoned and a feral population became established. Feral cats are now widespread throughout the state with sightings occurring in such remote areas as southwest Tasmania and the central highlands.
Cats are formidable hunters...
The cat is a carnivorous mammal and is very well adapted to hunting small mammals and birds. Being largely nocturnal hunters, cats may travel for several kilometres at night in search of prey. Cats have excellent eyesight, hearing and sense of smell. They can detect the smallest movement and can hear the scratching of a mouse many metres away.
Cats can also find their prey just by following the scent trail left by small animals as they move along the ground. They are also very able climbers. All of these features together with four sets of retractable claws, and teeth adapted for gripping, tearing and shearing, make the cat a formidable hunter.
...and ruthless predators
Feral cats prefer live prey but do occasionally scavenge carrion or human food scraps. They are opportunistic predators meaning that their diet generally reflects the fauna present in the area where they live and hunt.
Rabbits are usually the staple prey in Tasmania while other food items include small mammals, birds, reptiles (particularly skinks), frogs, fish, invertebrates and even vegetable matter. Where rabbits are absent or in low numbers -- for example in western Tasmania -- the diet mainly consists of small native mammals and native birds. Unfortunately native birds well outnumber introduced birds in the diet of feral cats in most areas of the state.
Domestic cats too!
Domestic cats often continue to hunt, even when fed on a regular basis. This is because cats instinctively react to movement, particularly rapid jerky movements. The prey is often left uneaten and may be brought home. Surveys of domestic cats reveal that the list of prey matches that for feral cats. Hence, domestic cats also impact negatively on native wildlife.
Toxoplasmosis: A hidden threat
Predation of native wildlife by cats is not the only reason for concern. Cats are the definitive host of the protozoan parasite Toxoplasma gondii which causes toxoplasmosis and is known to induce abortion in sheep and to infect humans and wildlife species. Toxoplasmosis can cause central nervous system and systemic disease leading to death in bandicoots and other wildlife species.
Female cats can breed before they are one year old. A healthy female produces two litters of kittens per year, usually during spring and summer, with an average of 4 kittens per litter. However, juvenile mortality amongst feral cats is high with the major cause of death being starvation due to food shortages during autumn and winter. Feral cats and kittens also fall prey to wedge-tailed eagles, white-breasted sea eagles, feral and domestic dogs and Tasmanian devils.
Where do feral cats come from?
Although there is a standing population of feral cats, recruitment is constantly occurring from the domestic population. Even the best kept cat can go wild, whether through wandering too far from its home area when hunting or via interactions with feral cats. Unfortunately unwanted domestic cats or kittens are often dumped by irresponsible owners. If they survive in the wild these discarded pets join the feral population and may breed with other feral cats if they have not been desexed. Feral cats are not just a problem in the bush. Indeed, a greater density of feral cats occur in and around cities, towns and rural settlements. This is probably due to more stable and abundant food sources being available in these areas. The presence of domestic cats may also attract feral cats to population centres.
How can you help?
The negative impact on native wildlife by feral and domestic cats can be minimised. If you own a cat the following suggestions can help reduce any impact your pet has (or could have) on native wildlife.
- If your cat is desexed it cannot breed with feral cats (whether it goes wild or not), and the inconvenience of unwanted kittens is also prevented. Desexing is a simple procedure that can be conducted at your local veterinary surgery.
- A cat's home range (the area in which it lives and hunts) may be reduced by up to 75% by detaining it at night. This often results in a substantial decrease in the number of native animals killed by individual cats overall. Cats that are kept in at night also live longer than those that are not. This is because they are not out fighting or mating with other cats or contracting diseases from them. Road accidents are also a major cause of death for domestic cats, so keeping them in at night greatly reduces this risk.
- Fit your cat with a collar and two bells, one on either side of the name tag so that potential prey are warned of the cats approach. Many cats continue to hunt successfully with a single bell. A second bell can reduce its chances of success.
- If you decide to purchase a cat, visit the Hobart Cat Centre. You can save one of these cats by providing it with a good home. All of the centre's cats are desexed and given a clean bill of health by a qualified veterinary surgeon.
Cats are remarkable animals and they make good pets. It has been shown that people who own a pet often live longer than those that do not. Hence a cat can be a very beneficial companion. With responsible ownership people can continue to enjoy their cat while at the same time protecting and enjoying our native wildlife.
Bradshaw, Dr J. W. S. (1993). The True Nature of the Cat. Boxtree Publishing, London.
C. Dickman (ed). (1996). Overview of the Impacts of Feral Cats on Australian Native Fauna. Australian Nature Conservation Agency, Canberra.
Strahan, R. (ed). (1983). Complete Book of Australian Mammals. Angus and Robertson, Sydney. p 488-9.