Effect of non-native species in Australia


Non-native species

Who introduced them

Reason for introduction

Effect on environment

Measures to control


i. How were non-native species introduced?

ii. Description of three non-native species in Australia

– Rabbits and fox

– Cane Toad

– Pear Cactus

Effect of Non-native species in Australia

iii. Effect on environment

iv. Conclusion


Non-native species are species, either animal or plant that are foreign to a place. Australia has a lot of non-native species introduced at various times and for various reasons. Non-native species are in animals, Aquatic life, birds and plants. Introduced species compete for resources with the native species. A non-native species is referred to as invasive if it has adverse effect of the native species. When non-native species outnumber the native it completely changes the fauna of a place.

Australian fauna is made unique by its exotic native species such as koala and kangaroos however other species have found their way in. One would wonder how the non-native species were introduced. In Australia some of the species were introduced as pets, some for economic reasons and others for pest control. It is suspected that the first non-native species to be introduced were the dingoes introduced by the native aborigines as pets. The largest inflow of foreign species came with the European colonialists. The Australian fauna was not impressive to the colonialist as it lacked wildlife that the colonialists were accustomed to. As a result they brought with them deer, rabbits, foxes and a wide variety of other species to provide food and for hunting as well as for sheer familiarity. In the aquatic life non-native fish species have been introduced for example the Tilapia. In addition, about one tenth of Australian plant species are foreign.

Australian fauna was largely unique may be due to its geographical isolation and unique climatic pattern. It lacked most of other species found in other parts of the world. A British colonialist Thomas Austin, for sport hunting reasons, brought 24 rabbits in Australia. The rabbits had high

Effect of Non-native species in Australia

fertility rate and increased at an alarming rate. Its population exponentially increased to over 200 million. The effect of this population was unimaginable. The rabbits, in competition with cattle, sheep and goats, devoured native grasses, bushes and trees turning grasslands and farmlands to a desert. This brought about diminished food, wiping out of brush hiding places and burrows for small marsupials thus their numbers were adversely reduced. Another introduction was European Red Fox, a predator. The predator preyed on the native mammals for example wallabies and rat-kangaroos. The combined effect of introduction of rabbits and fox was adverse reduction of the population of native endemic mid-sized mammals (McCallum,1995).

Non-native plant species were introduced as pasture for animal, raw material for industries, tree species for wood and for ornamental purposes. Many of these species have been declared as weed and have little contribution to agriculture in Australia (Lonsdale, 1994). A good example is Pear Cactus, which was brought into Australia as a hedging plant. It was aimed at keeping animal under control but quickly increased and ran out of control thus taken over the deserts.

In 1935, with an aim to control Frenchie beetle and Grey Backed beetle in sugarcane farms, the mighty Cane Toad was introduced. It was a misguided experiment for the toad didn’t generally feed on these pests. The toad succeeded in feeding on other native insect species almost to extinction (Young, 2000). In addition the poisonous toad would kill any predator that would try to eat it. Its prevalence continued to grow thus out-competing other amphibians and spreading diseases.


Introduction of foreign species has economic ecological and environmental effects. It has contributed to undistinguishable effect on Australian fauna. Some of the native species have been led to extinction. For example the Paradise Parrot which disappeared with introduction of livestock. Concerted efforts however have been put to reverse the effect. For example a lot of effort has been put to eliminate the rabbits by introduction of diseases. Unfortunately the control is expensive and not selective as such thus affecting native species. Native species have been an identity for Australia. It is a source of attraction for tourists. More resources should be used to

Effect of Non-native species in Australia

protect native species and thus conserve the environment.


Freeland, W. J; (1984):- Cane toads: a review of the biology and impact on Australia; – Winettie:

– NT parks and Wildlife Unit NT

Crotty, & Roberts, D. (eds) (2006):- The great mistakes of Australian history;- Sydney UNSW press (chapter 5)

Abrams, (1996): Evolution and the consequences of species introductions and deletions; Ecology 77


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