Fences have marked and protected land for thousands of years, and Australia happens to be home to some of the largest ever built. Three enormous barrier fences run across the continent, each raised to hold back an animal that was eating the country's farmland alive. They are worth knowing about, both as feats of fencing and as a lesson in what a wire barrier can and cannot do.
The Dingo Fence
The Dingo Fence is considered the longest fence in the world, running roughly 5,600 kilometres across three states, from the Darling Downs in Queensland to the cliffs of the Nullarbor above the Great Australian Bight. A stretch of it crosses the red sand dunes of the Strzelecki Desert. To put the length in perspective, it is several times the length of the Great Wall of China.
Construction began in the 1880s to separate the fertile, populated south-east from the harsh outback, and the fence was fortified in the early 1900s. It is a simple structure at heart: wire mesh about 1.8 metres high strung on posts driven into the ground, with some South Australian sections carrying a multi-strand electric wire. Crews patrol and maintain it year round.
What the Dingo Fence was built for
The fence was raised to keep dingoes, Australia's largest land predator, away from the sheep flocks grazing southern Queensland. Once it went up, dingo attacks dropped and flocks grew. It has never been perfect: dingoes still get through and even wild camels occasionally crash into it.
The downside of the Dingo Fence
Keeping the dingoes out changed the country on the fence's inner side. With the top predator gone, kangaroo numbers rose sharply, and kangaroos and sheep now compete for the same sparse grazing. Ecologists describe a single ecosystem split in two, with noticeably less small-mammal diversity and thinner grass cover on the dingo-free side, an effect large enough to be visible from satellite imagery. A fence, it turns out, keeps out more than the animal it was built for.
The Rabbit-Proof Fence
Before dingoes were the problem, Western Australia was fighting rabbits. Released for hunting in the 1800s, rabbits bred into the tens of millions and tore through crops across the continent, clearing flimsy fences with ease. In 1907, Western Australia finished a wire fence running north to south, more than 1,800 kilometres long, to hold the outbreak back. At the time it was the longest unbroken fence in the world.
Today it is known as the State Barrier Fence of Western Australia, linked with the State Vermin Fence and the Emu Fence, a set of pest-exclusion fences built in the early 1900s to protect Western Australian grazing land. Together the three run to several thousand kilometres.
The Darling Downs-Moreton Rabbit Board Fence
Along the Queensland-New South Wales border runs the Darling Downs-Moreton Rabbit Board Fence, built and extended over more than a century to keep rabbits out of Queensland's farming country. In 1997 its final segment was connected to the Dingo Fence. Sections of it are still actively patrolled and upgraded today, and by 2021 it had grown to around 555 kilometres.
What these fences tell us
For all their scale, these fences do the same two jobs every fence does: mark a boundary and protect what is behind it. In a suburban yard the rear fence is usually taller because it is guarding the property, while the front fence is a tidier way to mark the line. Even a fence low enough to step over still carries a plain message, that the line should not be crossed and what lies beyond belongs to someone else. The Dingo Fence just makes that point 5,600 kilometres at a time.