Australia's Feral Animals

The animals in Australia are unique, and in cases like the Koala, Kangaroo and the Emu; are only found in Australia.  Unfortunately if a new animal is introduced into this very fragile ecosystem the the whole thing could collapse, which will lead to many animals becoming endangered or extinct. Unfortunately this has already happened in the case of many animals, and the cause of the extinctions are Feral Animals.

Feral Animals are animals that have been brought in by settlers for sport or to make there new land feel more like home.  The reason that these new animals have such a huge impact is that Australia's native animals have evolved to fight off or eat the native animals, not the introduced ones, so without any natural predators to keep the population down then the feral animals can thrive in there new environment.  They also compete with the native animals for food and shelter, and since most of the feral animals eat the grass right down to the roots there is no food left for the native animals.  They may also carry many new diseases that native animals have not built up an immunity too; so if a native animal becomes infected then it could quickly spread and eventually wipe out an entire population. 

Most conventional control methods, such as fencing and baiting have not worked and it looks like that total eradication of the feral animal population in Australia is, at this time, just not possible.  

Examples of Feral Animals in Australia

Cane Toad

The cane toad was originally imported from Hawaii and South America to Australia to control the Cane Beetle outbreak that was effecting the sugar cane industry.  From when they were imported to when they were released the Cane Toad population had reached over 3000 toads, they were released into the cane fields in 1935.  The farmers hoped that they would soon eradicate the Cane Beetle, but they were very wrong.  Since the farmers had done little to no research into the Cane Toads behavior they had no idea that the Cane Toads would completely ignored the Cane Beetle because they were too had to get too, thus the Cane Toad left the farms and started to spread, and since each female toad can lay 8000-35 000 eggs at a time the population quickly climbed to hundreds of thousands of toads. They can now be found mostly on the eastern coast of Australia from Port Macquarie up to Cairns, but unfortunately they have just crossed to border of Kakadu National Park, and if left unchecked could destroy the very fragile ecosystem.   

The reason that Cane Toads are such a pest is that they are poisonous in all stages of there life, from Tadpole to Adult, and have very few natural predators.  The Cane Toads also kill native animals that hunt frogs and toads, thinking that they are harmless, but once they eat the toad they are dead in a matter of minutes.  However some animals have learned different methods of killing the toads and avoiding there poison, these animals are; the Wolf Spiders, Freshwater Crayfish, Estuarine Crocodile, Crows, White-Faced Heron, Kites, Bush-Stone Curlew, Tawny Frogmouth, Water Rats and the Giant White-Tailed Rat.  These animals have learned where th4e poison glands on the Cane Toad are located and have developed ways to avoid them.  These include, breaking the Toads jaw open and eating in innards, or flipping the toad over and attacking its stomach. 

To date the only way to reduce toad numbers has been to kill any you see, whether that was by hitting them with golf clubs, running them over or by freezing them, and the only way to keep them out of the garden was to build a fence and to make sure not toad could get in.  Nowadays new ways are being devised, the CSIRO has been investigating gene therapy as a way to control Cane Toad populations; there plan is to release a generation of sterile toads, that would in turn produce sterile offspring, hopefully dropping the population by huge numbers.  

Feral Pigs

Pigs were first introduced to Australia as a food source for the early settlers unfortunately many of those pigs escaped and are now thriving in the Australian Bush.  They can be found as far as the Kimberly region in Western Australia, down to Western Victoria.  Since they escaped into the wild there populations have been growing at a rate of 80 to 110% per annum, and if the conditions are right then they can bread all year round, causing a big problem for those who are trying to wipe them out.

Feral pigs are such a huge problem because they are omnivores, which means they will eat both plant and animals. They eat many farmers sheep and injure cattle, but the big problem is they eat fruit, roots, beetles, reptiles, crocodile eggs, young rabbits and other small animals, as well as scavenging on dead remains.  Since the pigs have such a varied diet they can destroy crops, pasture and fences, and ground birds are also at risk, and because they are hard hoofed animals they can destroy animal burrows and erode creek and river banks.  

The main control method that is used is to muster the pigs using helicopters and shoot them, but this will only be effective in the short term.  However pigs shot may be exported and used as meat, in 1990 1500 tonnes of  pig meat was exported to European countries. 

Feral Cats

Cats have been living in Australia since to early days of settlement, but there is a theory that they have been here longer, stranded when Dutch ships crashed.  Cats were introduced to control populations of Mice, Rats and Rabbits, but by the 1850's a large population was established in the wild. Cats are unique animals in the sense that they can very easily adapt to new surroundings, very quickly; which is why they are found in most areas of Australia and on some offshore islands.

Cats instinctively eat small mammals, which is bad news for some of Australia's native mammals, such as the Bilby and the Bandicoot, they will also eat Birds and Reptiles. Cats also impact greatly on native fauna, this is a problem especially on islands because once the trees there are gone then no new plants are going to grow.  There has even been been cases were Feral Cats have been directly responsible for the decline of of a threatened species that has been on the recovery for many years.  

So far they easiest way to control the cat population is to shoot them, and that has been successful on islands as the cat population has been eradicated, but on the mainland it is a different story.  Although shooting does work people can not find and kill them fast enough to seriously effect the population.  Another way is to trap them, but cats are very cautious around things they don't understand and will avoid traps, so people are trying to use lures to attract the cats into the traps, but it looks like it will take many years before the cats are completely gone from Australia.  

Rabbits

Rabbits arrived in Australia with the first fleet, but they did not become a serious problem until 1859 when Thomas Austin released 24 rabbits on to his property for sport, but because of that mistakes rabbits can be found from the north-east of south Australia and up the east coast, but they generally don't go above the tropic unless conditions are favorable. 

Rabbits cause a big problem because they burrow into the sides of hills and creeks causing erosion, they also destroy many crops and there seedlings the plants won't grow again, and it is estimated South Australia's losses are up to $20 million a year.  Rabbits reach sexual maturity around 3 to 4 months after been born, so they can breed fast and can produce litters of 4 to 5 young every month; which is why it is hard to control the populations. 

In the past the only way to control them has been to shoot them, but climate has also proved effective in reducing number but it has just not being enough.  However the government has authorized the use of a virus called Rabbit Calicivirus Disease (R.C.D)  The virus spreads from rabbit to Rabbit, not by insects and it is species specific so it will not harm native animals.

Summary    

Australia is a land full of unique animals, but they have been invaded by feral animals such as: The Cane Toad, Rabbits, Cats and Pigs.  They destroy native plants and animals and also erode the land.  Since conventional methods; such as Trapping and Culling, have not worked it is up to new viruses and techniques to kill these invaders, but now it seems it may not be possible to rid Australia of Feral Animals.