Australia is divided by sport (the Barassi Line) and by topography (the Great Dividing Range), but perhaps its most iconic division is a basic two-metre-high fence. Basic, perhaps, by its construction (wire mesh extending 180 cm/6 ft high and 30 cm/1 ft deep), but certainly not by length: at 5 614 km (3 488 mi) in length, the world’s longest fence, known as the Dingo Fence or Dog Fence, has split Australia in two for the past 130 years.
Source: Roke, http://commons.wikimedia.org/wiki/File:Dingo_fence_in_Australia.PNG. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.
Dingoes, the wild dogs of the Australian continent and the largest carnivorous mammal in the country, were seen as a nuisance animal on agricultural lands dating back to the beginning of European settlement in the region, predating on the valuable sheep flocks that cover much of southeastern Australia. Bounties were (and are) placed on the heads of dingoes in southeastern Australia as early as 1852. To say the bounty programme was popular would be an understatement: 286 398 bounties were paid out between 1883 and 1930, peaking in the 1890s. While bounties were placed on numerous types of animals, the bounties given for dingoes were generally the highest; often twice as much money was given for a dingo than for other ‘pests’ such as foxes, hares, and wallabies. The most effective method of preventing dingoes from killing sheep in southeastern Australia, however, was to stop them from entering it in the first place.
Dingo Fence, Breakaways Reserve, South Australia, Australia. Source: raguy, http://www.flickr.com/photos/raguy/4208880426/. Licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0) licence.
The fence as we know it today was not a singular construction but rather the coming together of multiple fences, and was not originally built to keep out dingoes. The backbone of the fence was constructed between 1880 and 1885 across southern Queensland as a rabbit-proof fence. While it failed in this task, larger fauna such as kangaroos, pigs, and emus were stopped by the structure. As the dingo population in southeast Australia began declining from the collection of bounties, the idea of using the fence to keep dingoes out of the region permanently was arrived upon. The 2 500 km (1 553 mi) Queensland fence (known as either the Great Barrier Fence or the Wild Dog Barrier Fence) was expanded and heightened beginning in 1914 specifically to stop dingoes, eventually to be joined with other animal exclusion fences across the southeast quarter of the country – the Queensland Border Fence, the South Australia Border Fence, and the section that stretches across South Australia known simply as the Dog Fence. Beginning at the Queensland village of Jimbour in the Darling Downs, the fence zigzags its way across Australia to the cliffs of the Nullarbor Plain above the Great Australian Bight. Initially, the landholders on either side of the fence were responsible for its maintenance; it was not until 1978 that the federal Department of Natural Resources and Water began actively patrolling and maintaining the edifice.
Dingoes are believed to have arrived in Australia around 4 000 years ago via Southeast Asia. The introduction of domestic dogs into the wild after European colonisationgreatly impacted the dingo population to the point where only a small percentage of dingoes, perhaps less than 20 percent, can be considered ‘pure’. Source: H. Whitehead, http://commons.wikimedia.org/wiki/File:Nullarbor_Dingo.jpg. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.
Over time, the length of the fence has been reduced by 3 000 km within Queensland for cost reasons (as recently as 1980, the fence was 8 614 km, or 5 354 mi, in length) and control over the dingo population is largely done via poisoning, specifically via bait laced with sodium monofluoroacetate (1080). While dingoes remain common in the northern half of Australia, they are almost non-existent in most places on the south side of the fence save for the strip of land between the Pacific Coast and the Great Dividing Range where no fencing exists; these tend to be exclusively dingo hybrids. Very faint populations exist immediately to the south of the fence. Despite maintenance and patrol, holes have developed in the fence over the years, particularly in South Australia, and dingo offspring are passing through them and predating on sheep on the other side, greatly affecting the ability of farmers to stay afloat (interestingly, government statistics show that between only one and seven percent of a typical dingo diet consists of domestic stock; generally half consists of kangaroos and wallabies). Feral camels are also smashing through sections of the fence in search of water (the effect of the more than 1 million feral camels on infrastructure in the outback is an increasing problem), and recommendations to reinforce and electrify portions of the fence have been made.
On the north side of the fence, where agricultural activity is less pronounced, dingoes largely roam free and in many cases are conserved, as many consider the generic purity of dingoes to be in grave danger due to hybridisation with feral domestic dogs. Here, red kangaroo and emu populations are less dense, with studies indicating that the presence of dingoes may actively regulate the population level of these speciesand that as the apex terrestrial predator on the continent, dingoes structure mammal communities and promote biodiversity.
Dingo and livestock distribution in Australia as a result of the Dingo Fence. Source: Inugami-bargho, http://commons.wikimedia.org/wiki/File:Wild_dog_distribution_2.png. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.
The Dingo Fence is not the only super-fence in Australia. The three rabbit-proof fencesof Western Australia, totalling 3 253 km (2 021 mi) in length, was constructed between 1901 and 1907 to keep feral rabbits and other animals out of WA grazing areas. While it failed to keep out the rabbits much as the Queensland fence (myxomatosis was later introduced in the 1950s to serve that purpose), it did keep kangaroos and emus out. Interestingly, it also kept precipitation out, as clouds are more prone to forming over the native vegetation on the east side of the fence than the engineered cropland on the west side.
Source: Roke, http://commons.wikimedia.org/wiki/File:Rabbit_proof_fence_map_showing_route.PNG. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.
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Associated Press (2009). Australia Plans to Kill Thirsty Camels. CBS News, 26 November 2009. Available at http://www.cbsnews.com/stories/2009/11/26/world/main5786556.shtml. Accessed 15 March 2012.
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Pople, A.R. et al. (2000). Trends in the numbers of red kangaroos and emus on either side of the South Australian dingo fence: evidence for predator regulation? Wildlife Research 27(3): 269-276. Available at http://espace.library.uq.edu.au/eserv.php?pid=UQ:9890&dsID;=trends_in_RK_Emu.pdf. Accessed 15 March 2012.
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