The Great Walls of Australia
Strictly speaking, there are three “walls” in Australia. The first of them was created to fight rabbits. In 1859 from England, a ship arrived in Australia on which there were twenty-four rabbits. Released (the name of the person who committed this thoughtless act - Tom Austin is known), these seemingly harmless animals, after 30 years, turned into a real disaster for all farmers. The population of rabbits grew exponentially, the struggle with them was ineffective, the fields and pastures of the Green continent were rapidly turning into a desert. To avoid ruin, many-kilometer fences began to be erected around the farms, which were originally created from various materials, mainly from different types of wood. Inspection of the hedge condition at the beginning of the last century was carried out on bicycles, and the position of chief inspector was called “inspector of rabbits”. On the side of the rabbits, termites unexpectedly emerged, by whose efforts the fences proved to be very short-lived. Feral camels and local kangaroos became other "allies" of rabbits. Currently, this fence obstructs the continent in half from north to south, its length is 3253 km. This “wall” was built by 400 workers from 1901 to 1907. Despite all the efforts, experts assume that currently rabbits eat annually a quantity of grass, which would be enough to feed 25 million sheep. Powerless was even "biological weapon»: Myxomatosis virus, which infected the caught individuals in 1950, and the calcivirus, which was introduced into their population in the 1990s. After the first (and very impressive) success, individuals resistant to these viruses appeared, and as a result, the number of rabbits recovered fairly quickly.
The Australian sheep breeders, whose herds were attacked by wild dingo dogs, had to think seriously about the fences around their farms and even more desperate.
Interestingly, a dingo can be seen, but only in Australia, but also in Thailand, the southeastern part of China, Laos, on the islands of Indonesia, New Guinea and the Philippines. Moreover, the oldest known remains of a science dingo dog were found in Vietnam: their age is estimated at about 5,5 thousands of years. But Asian dingos are smaller than their Australian relatives. It is assumed that these non-killing predators, the size of a small wolf, are descended from feral dogs that were brought to the continent from Asia more than three and a half thousand years ago by people who came from the islands of Southeast Asia (presumably Sulawesi and Kalimantan). That is, dingoes are secondarily wild animals. The oldest remains of these dogs, found in Australia, are about 3400 years old.
The usual color of these predators is red, or gray-red, but there are groups with gray or even black color. It is believed that this is the result of mixing dingos with migrants' domestic dogs. The dingoes quickly supplanted the few local marsupial predators (the marsupial wolf was their main competitor for a short time) and began to live hunting for kangaroos, birds, and reptiles. Later, they included rabbits and sheep in their diet, but they can also bull calf.
Moreover, sheep became the easiest and most desirable prey of dingos. By attacking the herd, in the excitement of hunting, dogs slaughter many more sheep than they can eat. One dingo family per night can slaughter a dozen sheep. People without dingo provocations are usually not attacked, but for Australian farmers this was a poor consolation. The fight against dingo began in 1788, when the first sheep were brought to the continent. The destruction of dogs was complicated by the dingo nightlife: during the day they hide in secluded places and go hunting only in the dark. Traps and trapping nets were set on predators, they were shot and poisoned. At the end of the 19th century, only in the state of New South Wales, farmers annually spent several tons of strychnine to fight wild dogs. For each killed animal a bonus was paid in 2 Shilling. (Now payments for a dog killed within a hedge can reach 100 Australian dollars). Large shepherd dogs brought from Europe successfully fought with their wild relatives. Nevertheless, all these measures taken to combat the "red misfortune of Australia" were not effective enough. In a short time, the dingo population has increased a hundred times, and there is a real danger of the destruction of all livestock. In 1880's In southern Queensland, the construction of a huge net fence was started. Other states followed the example of their neighbors, and by 1901, the entire southwest of Australia was pulled up and down by a wire net. In the mid-twentieth century, farmers and local authorities came to the conclusion that in order to more effectively combat predators, a disorderly network of different-sized hedges needs to be replaced with a single fence, which will be supported by deductions from the ranchers' profits.
As a result, in 1960, three sheep state - Queensland, South Australia and New South Wales - combined their protective fences into a single wall of wire mesh dug into the ground to a depth of 30. Currently, the length of this fence is 5 323 km, height - 180 see. It almost completely crosses the continent, not reaching the western coast of the mainland only 180 km.
The point, of course, is not in the laziness of the Australians and not in the lack of funds, but in the purely agricultural specialization of the non-enclosed areas: the dingos simply do not go there. Some of its sites are over a hundred years old. Others have been built recently and the repellent current produced by solar panels is passed through their wire. In areas where there are many foxes, the fence is cemented in order to avoid digging. And in places of mass concentrations kangaroos increase the height of stakes. Keeping the fence in good order is not cheap: Queensland New South Wales and South Australia spend about 15 million Australian dollars annually for these purposes. It is necessary to restore the integrity of the grid quite often - floods and rains wash away supports, and rust thinns and destroys the grid. In addition, wild camels, kangaroos, emus, tear foxes, anteaters and wild boars, tear her up. Years of experience have shown that dingos cannot break through the net, but they do not miss the opportunity to use any breach to penetrate the territory forbidden to them. And because of this, special caretakers inspect every kilometer of the hedge every day, looking for damage in the grid and underground holes made by rabbits or wombats, and destroying the dingos that penetrated the fence. Previously, they traveled by camel, now at their disposal powerful jeeps.
The third Australian wall is not so large, the length of the entire 44 km, but quite high - 3 meters. It surrounds the national reserve Newhaven and protects its inhabitants from ... feral cats.
There are about 20 millions in Australia, and, meanwhile, it is estimated that all 200 cats annually consume about 100 thousands of rabbits, birds and small animals. Wild cats are supposed to kill more than 3 millions of birds, reptiles and mammals every day — about 2 thousands per minute! Australian authorities plan to create a predator-free area of about 9400 hectares.
Now Australia is hastily going to build another barrier, this time to protect against reed toads. In Europe, these amphibians themselves are on the verge of destruction, but, carelessly brought to Australia and not having natural enemies there, they quickly multiplied, “colonized” the state of Queensland and are now moving to the north-west. The real danger threatens the national park on the Coburg peninsula. Scientists fear that if they fail to block the path of the toad hordes, many species of insects and small animals will be destroyed. To stop the toads should 9-kilometer fence that crosses the isthmus. Cane toads do not know how to jump, but they dig deep enough holes, and therefore the concrete wall just above half a meter should be almost as deep.
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