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Ferals and Exotics

Many of the animals that live in Australia were introduced here from other countries. In some cases, the introduction was deliberate, while in others it was accidental. Some are obvious–such as sheep, cattle, and water buffalo, while others are less obvious–such as dingoes, trout and sparrows.

GoatThere is a distinct difference between feral animals and introduced wild animals.

Ferals are formerly domesticated animals (livestock), that have become established in the wild. Examples include feral cats, pigs, goats and feral horses (brumbies). Exotics, on the other hand, are introduced animals that were not originally livestock. They came into the country for many reasons. For example, the cane toad—now a serious pest—was brought in to help sugar cane growers by eating two insects that damaged sugar cane crops; deer, rabbits and foxes were introduced to give wealthy colonists a game animal to hunt; the common house mouse came here by accident; and the honeybee was deliberately released into the wild.

Introduced animals have had a profound effect on Australia’s flora and fauna. Just some of those negative impacts include:

It may be impossible to totally eradicate imported species, especially those with a proven ability to adapt, such as the rabbit. However, control may be possible to the point where the feral or exotic has a minimal effect on native species. Sometimes, it is simply not socially, economically or even technologically feasible to attempt to control pests, as their numbers may be directly related to the seasons; in other words, in a good season the numbers increase and in a bad season the numbers decrease, without human intervention.

The students will best be able to identify with the more common feral or exotic animals.


Rabbits are probably the best known of Australia’s introduced animals. Domestic (tame) rabbits were brought out on the First Fleet, but it wasn’t until 1859 that two dozen wild rabbits from England were released onto a farm in southern Victoria. Just seven years later, on that same farm, over 14 000 rabbits were hunted in one year! Another property owner estimated he had destroyed over 2 000 000 rabbits in the 10 years after their introduction – just on his property. It has been estimated that, at their peak, there were a billion rabbits in Australia!

The damage they caused was almost incalculable: they destroyed vegetation; they competed with native species for food; they attracted foxes and feral cats, which also preyed on native species; they stripped plant cover from the ground, leading to massive areas of soil erosion.

In the 1950s, a disease called myxomatosis was introduced to Australia. Within years, it had reduced rabbit numbers from an estimated 600 million to approximately 100 million. This was followed in the 1990s by the release of the calicivirus, which has further devastated numbers.

Nevertheless, in many areas, rabbit numbers appear to be again on the increase.

Cane toad

This is a classic example of good intentions that went wrong! In 1935, the cane toad was introduced into Queensland; its mission—to control two existing insect pests that were detrimental to the sugar cane industry.

The cane toad adapted well to the Australian environment, and with a little help from ‘unofficial’ releases, was soon spreading like wildfire. Barely 50 years later it had crossed into the Northern Territory.

Oh, yes – five years after the cane toad’s release, an insecticide was developed to kill the insects anyway!


The fox was introduced for hunting in 1845. First released near Melbourne, within 50 years it had crossed the Nullarbor and was found in Western Australia. Tasmania until recently was thought to be fox-free. However, new sightings seem to confirm the authorities’ worst fears – foxes are established in Tasmania.

Foxes are traditionally blamed for stock losses, especially chickens and baby lambs. While this may be the case, the hidden danger has been their attacks on native wildlife, such as the numbat and the quoll. With rabbit numbers so low, many scientists believe foxes are turning to small native mammals as a food supply.

The traditional form of fox control is a combination of shooting and poisoning. This has enjoyed a good deal of success, but is an expensive operation, especially since the market for fox furs has collapsed.

Feral cats

Cats may have arrived in Australia following early Dutch shipwrecks off the coast. (Cats were taken onboard to control rats and mice.) In the 1800s, cats were deliberately released into the wild – to control the other introduced pests of rabbits, rats and mice!

Cats are extremely accomplished hunters, and can survive in dry conditions, using moisture from the body of their prey. Their diet consists of small mammals, birds, reptiles and insects. They do eat young rabbits, but as do foxes, will turn to native animals as rabbit numbers decline in any area.

Cats are extremely difficult to control by conventional methods, and a great deal of research is currently being undertaken in this area.


Despite the sorry history of introducing animals into Australia, many people still attempt to smuggle exotic fish, birds, even reptiles and plants into the country. It appears some still haven’t learnt the lessons of the past.