Invasive species fact sheet
Environment Australia, 2002
A species is considered invasive if it spreads into new habitats and upsets the natural balance. For example rabbits eat the native vegetation and aggressively compete with native animals displacing them from their homes. Invasive species cause problems in both natural and agricultural environments. Invasive species are one of the biggest threats to biodiversity.
They include animals and plants that were deliberately or accidentally brought into Australia since European settlement 200 years ago. Many of the invasive introduced animals and plants, e.g. foxes and lantana, don't have natural predators or diseases in Australia, so they multiply and grow out of control. It's important to remember, though, that not all introduced species become invasive. Some introduced species are not aggressive. Examples include crops such as rice and wheat that are also economically important to Australia.
It is not commonly known that native species can become invasive too. Some native animals and plants when taken out of their natural habitats and introduced where they don't belong 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.
Introduced predators eat our native animals, like the pretty marsupial Bilby. Bilbies also have to compete with introduced animals for living space and food and have their habitats degraded by other introduced animals. Invasive plants compete with and replace native plants that are needed to provide native animals with shelter and food. In so doing, they can upset how the natural ecosystem works and destroy the habitat.
- Invasive introduced animals cover a wide spectrum of different species. While many species may be familiar such as foxes, feral cats and rabbits, some lesser known examples include the red-eared slider tortoise and the yellow crazy ant. Other problem species in Australia include camels, starlings, the mosquito fish (Gambusia), cane toads and the northern Pacific seastar.
- Some of the species above are domestic animals gone wild, like feral cats, or animals introduced into Australia for another purpose, like foxes and rabbits for hunting and Gambusia to control mosquitos. Others, like the seastar, were accidentally introduced and some were originally pets, for example the red-eared slider tortoise.
- Our main concern is that invasive introduced animals are destroying Australia's native wildlife and native habitats.
- For example, feral water buffalo have hard hooves that destroy habitats by eroding soil and trampling vegetation.
- Feral cats and foxes hunt and kill native birds, mammals, reptiles and insects and are a threat to the survival of many native species.
- In the past people have controlled feral animals by fencing, trapping, poisoning and shooting. Today, scientists are experimenting with biological controls of feral animals, such as introducing methods to control their breeding.
- Invasive plants that threaten the environment sneak up on us without our noticing them. It's very important to jump on them quickly before they take root where they don't belong - in our National Parks, natural areas and farms. Introduced into the wrong areas, invasive species like bitou bush and willows* can cause enormous problems.
- Many of our invasive plants, such as lantana and hymenachne, were introduced as garden or pasture plants.
- Invasive plants use up valuable space, food and sunlight that are normally home to native plants. They also replace native plants that animals use for shelter, food and nesting.
- Even some native plants, such as sweet pittosporum and bluebell creeper, can become weeds when they grow in areas outside their natural range. Invasive plants spread their seeds far and wide, through the wind, the creeks and rivers, by birds and animals and people. * except Weeping Willows, Pussy Willow and Sterile Pussy Willow
- Learn more about the plants in your garden and how they spread - are any of your garden plants really invasive plants in disguise? Replace any garden plants that may spread and be careful what you plant if you live near waterways, farms or bushland.
- If you suspect an invasive plant is growing in your garden, you can identify it by taking a fresh sample in a paper bag to your local council or State Department of Agriculture or Environment
- Cover trailer loads when taking waste to the tip.
- Get involved in Weedbuster Week each year www.weedbusterweek.info.au
- Become a responsible pet owner. Is your pet dog or cat desexed and properly cared for? Learn what you can do to minimise any damage pets do to native wildlife.
- If you have unwanted pets, including dogs, cats, birds and fish, do not release them into the bush. Talk to your local council or RSPCA to get advice on finding them a new home.
- Become a volunteer with your local Bushcare, Landcare or Friends group and help to replace the invasive plants with native plants and repair any damage to the habitat caused by invasive animals.
The Australian Government is helping farmers and State Governments work together to control feral animals and plants to ensure the long-term survival of Australia's native species.
Check out these web sites for more information:
- National Weeds Strategy http://www.weeds.org.au
- Western Australia Department of Agriculture: http://www.agric.wa.gov.au/progserv/plants/weeds/links.htm
- Queensland Department of Natural Resources http://www.nrm.qld.gov.au/factsheets/groups.phtml?group=Pest
- Victorian Department of Natural Resources and Environment (search under plants and animals): http://www.nre.vic.gov.au
You can also find out more information about Australia's threatened species by calling the Department of the Environment and Water Resources Community Information Unit on free call 1800 803 772