Environment Australia, 2002
About the fact sheet
Invasive species have had devastating effects on our soil, native vegetation or wildlife. Feral animals like cats and foxes hunt and kill numerous native birds, mammals, reptiles and insects. They also compete with native animals for space, food and shelter. Weeds change the natural balance by smothering native plants or preventing them from growing back after clearing, fire or other disturbance.
Native animals are put under increasing pressure when the native plants that are used for shelter, food and nesting are replaced by weeds. Lantana, found in many back yards, is a major threat to many species, including plants such as the endangered Hairy Quandong.
Introduced predators such as foxes and cats are a major factor in the disappearance of native animals such as the numbat from areas where they were originally found.
It is important to remember that not all introduced species become invasive - crops such as wheat are not invasive and are also economically important to Australia. Sometimes native species can become invasive too. If introduced where they don't belong they can grow out of control. Cootamundra wattle has become a problem in many regions, as has the Yabbie in parts of Tasmania where it did not originally occur.
It's not easy to stop the actions of invasive species, and years of careful planning and research are needed to do the job properly. Although there are control methods - like trapping, shooting, and poisoning for invasive animals, and weeding and spraying for invasive plants - they must be applied without further harming our native wildlife.