When a population grows really, really quickly, producing young at rapid rates and overall numbers skyrocketing out of control, we know precisely how to describe that situation. We say that the thing, whatever it is, is breeding like rabbits to convey that idea of unchecked growth.
For most of us, that concept is simply a metaphor we have tucked away, ready to use whenever we need it.
When the metaphor itself becomes a real-life issue, then we have massive problems.
Cut to Australia in the early twentieth century, when quickly-multiplying rabbits was anything but a metaphorical situation. Australia’s rabbit infestation spiraled out of control so dramatically that the Public Works Department of Western Australia was forced to build huge fences to curb rabbit activity. These fences are so big that they can be seen from outer space.
Gigantic, thousands-of-kilometers-long fences? To keep rabbits at bay? Adorable, fuzzy, tiny little bunny rabbits? Doesn’t that seem like an overreaction? A side-project that, on the whole, we could have very likely skipped?
Let’s talk about the realities of having far too many rabbits hopping around, eating up vegetation and changing the local ecology, and then you decide. We’ll start in the before-times, when Australia’s rabbit population was underwhelming. One newly-settled English colonist took issue with that – and the rest is history.
Setting the stage.
The first European rabbits came to Australia when the first Europeans did: in the First Fleet. In May of 1787, eleven ships departed from England and headed to Australia to form the initial penal colony of New South Wales. That First Fleet consisted of a few civil officers and marines, a good quantity of supplies, and between 1000 and 1500 convicts. Somewhere on that boat, camouflaged in a corner, there must have been a small family of rabbits aboard, too.
New South Wales set up its new Southern hemisphere life happily; so too did the stowaway rabbits. For about 80 years, humans and rabbits lived together in peace. In fact, the Australians caught and bred the rabbits for food. Occasionally, they used the tiny hides to line shoes or mittens. Judging by analyses of Australian colonial food remains, it wouldn’t appear that the rabbits were especially numerous.
By the 1820’s, that began to change. One contemporary newspaper noted that “…the common rabbit is becoming so numerous…that they are running about on some large estates by thousands.” This seems overwhelming, but, at the time, New South Wales wasn’t yet concerned. One NSW resident was still remarking on the ideal conditions for breeding more rabbits in 1827, writing, “…rabbits are bred around houses, but we have yet no wild ones in enclosures.” Then, the idea of rabbits shortly taking over the continent might have seemed, to us, like the prospect of an angry horde of chihuahuas roaming the globe. It just didn’t seem likely—or particularly problematic.
In the 1840’s, people were still breeding rabbits for food. Their numbers may have been starting to grow slowly: Records from NSW’s courts show that rabbit thefts were increasingly common.
The main event that triggered out-of-control rabbit growth happened in 1859.
The problem arrives.
1859: Property owner Thomas Austin, who had just moved to Australia, decided that he missed hunting. In England, he’d often dedicated his weekends to shooting rabbits. He wasn’t able to do that in his new home. Thomas wrote his nephew William, back in England, to send him a specified list of game: 12 grey rabbits, 5 hares, 72 partridges, and some sparrows. He wrote, “The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting”.
Unfortunately, William wasn’t able to find enough grey rabbits to fulfill his uncle’s order, so he sent over a larger number of domestic rabbits, hoping it would make up the difference. (Another source states that some 25 domestic European rabbits made their way to Austin’s estate.)
It would seem Austin wasn’t very good at hunting. The native population of Australian rabbits skyrocketed out of control by the mid-1860’s. (By 1866, a newspaper reported that some 50,000 rabbits had been killed by hunters—which failed to make any dent in the rising population.)
How was this happening? These rabbits were multiplying like crazy.
European rabbits are known for producing large amounts of offspring. They can also start to reproduce when they’re very young. They tend to have four litters per year, each with two to five ‘kits’. This results in a LOT of rabbits extremely quickly.
Here’s the other thing: Australia was the perfect place for a rabbit population to explode. Australia has mild winters, which meant that rabbits could breed the entire year. The widespread farming happening at the time leveled forest and scrubland—places where it would have been difficult for rabbits to nest—into fields with low vegetation; a rabbit’s paradise.
Too much of anything – perhaps, especially rabbits! – is a problem. The havoc rabbits were wreaking on Australia’s ecology was devastating.
How did they do this? Primarily through overgrazing and reducing the availability of natural resources for indigenous species. Rabbits reduced natural pasture vegetation first, and then ate away woody vegetation such as small shrubs and the bark of small trees. This decimated Australia’s natural flora, upon which Australia’s natural fauna was dependent.
Rabbits also caused serious erosion problems. They ate away Australia’s plants, which left the topsoil exposed. When winds swept across Australia’s plains, followed by driving rains, the topsoil wore away. No topsoil makes it very hard to regrow any of the vegetation lost to rabbits—or promote any type of commercial agriculture, something Australia was trying very hard to do at the time.
Farmers started to suffer huge problems as the number of rabbits continued to grow. They started building individual fences to ensure that the rabbits couldn’t reach their personal crops. Farmers also dedicated a lot of time to destroying rabbit warrens—or the underground tunnels that rabbits create through burrowing. Farmers would find them and destroy them. Rabbits breed and raise their young in these warrens—which means that removing them can be an effective way to control smaller rabbit populations.
By 1887, “losses from rabbit damage” compelled the New South Wales Government to offer a £25K pound reward – nearly £2M in 2021 – for “any method of success not previously known in the Colony for the effectual extermination of rabbits.”
The result of their investigation? They’d noticed the success of farmers’ small fences. It was time to build a very big one.
Building the fence
Now, this wasn’t the first time Australia had decided to build a large fence.
Before Australia’s rabbit population spiraled out of control, the continent had a dingo problem. These wild dogs regularly attacked sheep and cattle stations. In one year alone, one station lost over 11K,000 sheep due to dingo attacks.
In 1885, Australia completed construction on a wire mesh fence to keep dingoes away from key sheep stations. Keeping half a continent of industrious dingoes out of these stations required a lot of fence. (There are sheep and cattle stations in Australia that are larger than small countries.) The Dingo Fence is one of the longest structures in the world, stretching 5,614 km (or 3488 miles).
The Dingo Fence worked, to an extent. Armed with this precedent, Australian construction workers broke ground on a new rabbit-proof fence in 1901.
Its primary goal was to keep rabbits out of Western Australia. The fence ended up being formed of three smaller fences; combined, running for 2,023 miles or 3,256 kilometers. It took six years to build, and the cost per kilometer of fence was AU$250 (or AU$19K in 2021 dollars). In 1907, at the time of the fence’s completion, its longest segment (at 1139 miles / 1833 kilometers) was the longest unbroken fence in the world.
Australia’s Rabbit Fence was made out of many things. For the most part, it consisted of posts made out of local wood (such as salmon gum, tea-tree, and mulga) spaced a few meters apart. In between each post was barbed wire or wire netting. When wood was scarce, construction workers used iron. They tried to minimize this, though, as iron is very heavy…and whenever they couldn’t use what was locally on hand, the workers had to haul in materials over hundreds of kilometers by bullock, mule, and camel.
As the project drew to a close in 1907, it was primarily under supervision of the Public Works Department of Western Australia, and one man in particular—Richard John Anketell. Anketell’s workforce consisted of 120 men, 350 camels, 210 horses and 41 donkeys. When the project transitioned from constructing the fence to maintaining the fence, a man named Alexander Crawford took over.
Even though the fence was already built, Crawford’s job was far from easy. In fact, maintaining the fence was when the troubles really started.
Maintaining the fence
Crawford employed four sub-inspectors, each of whom was responsible for 500 miles / 800 kilometers of fence. Under these four worked 25 boundary riders. These thirty men had a big job in front of them.
Remember, this was the very early twentieth century. We didn’t have very many ways to reliably or quickly communicate long-distance, and we certainly didn’t have CCTV to provide remote monitoring.
In order to make sure that the fence did its job—keeping huge numbers of insidious pests away from Australia’s dwindling natural resources—people from Australia’s fence-protection squad had to set eyes on the fence themselves. This meant that Crawford’s team had to figure out a way to travel up and down 3,256km of fence pretty frequently.
To do this, they experimented with several modes of transportation.
They began with bicycles, but found that this wore out the maintenance workers. Quickly, the boundary riders upgraded their rides to camels.
While this was much easier on their legs, it proved very difficult for their necks. The camels were taller than the Australian Rabbit Fence, and peering downward to assess potential damage didn’t really work for the boundary riders, either.
In 1910, the team leveled-up their maintenance transportation again, purchasing a car to inspect the fence. Unfortunately, this didn’t work either. The car’s tires were no match for the rugged, rocky, ever-changing Australian terrain. The tires punctured very quickly.
Eventually, the team settled on a novel idea: Each maintenance team got a ruigged sled consisting of a buckboard buggy tied to two camels. This makeshift vehicle carried two increasingly uncomfortable maintenance workers, sand-surfing alongside the Rabbit Fence, for miles and miles in what must have been the bumpiest maintenance route of all time. (Between their assistance as pack animals during the construction phase and their integral role pulling buckboards for maintenance, there are those who believe that it would have been impossible to build the fence without the use of camels.)
After the sub-inspectors and boundary riders had figured this all out, Crawford still had to complete his own job. His job was to eliminate in real time any rabbits that managed to breach the fence. In other words, he set out each morning to play a real-life, high-stakes version of Whack-A-Mole. Unfortunately, the state of the fence made this necessary: In just the first year following the completion of the fences, a large number of rabbit colonies was found and eliminated on the wrong side of the fence.
The Australian Rabbit Fence was a major topic of cultural interest at the time, serving as the inspiration for many books and, later, movies. Comics and jokes lightly roasting the fence appeared in Australian newspapers quite often, with one highly-circulating comic hinting that, well, of course the rabbits were finding ways to breach the fence; the critters were using it as a government-sponsored net for their games of rabbit tennis.
Did the rabbit fence work?
After a while, Crawford’s team had to face the truth: The fence wasn’t working as well as they’d hoped.
Fences work really well in theory—but they must be regularly maintained. They’re perfect for small-scale solutions, but over thousands of kilometers, constantly subject to weather conditions and extremely industrious pests, these walls just couldn’t do a 100% effective job.
Unfortunately, rabbits—and their intensely packed breeding schedule—demand 100% efficacy. Eliminate 95%, and the remaining few will repopulate very quickly.
There’s also the idea that, perhaps, these fences were doomed to begin with. Since building them took a very long time (remember, all construction materials had to be brought to site by camelback), rabbits were almost always able to bypass the line of the fence as it was being constructed, leading to equal numbers of rabbits on either side of the fence as soon as it was completed.
One commentator put it this way: ‘At best, the long barrier fences merely delayed the spread of rabbits into new country’.
It was time to come up with a new plan.
Searching for an effective plan B
A physical fence can break down, and particularly creative rabbits can burrow deep or leap through holes. In the ‘50s, the government tried another solution. They teamed up with Australian scientists to release another wave of rabbits into the wild; but this group of rabbits leapt into the bushland carrying the myxoma virus—a specific viral strain that only affects rabbits.
This massive experiment was the first time scientists ever purposefully introduced a virus into the wild to eradicate an entire species. One Australian scientist said, “Thus, inadvertently, began one of the great experiments in natural selection, conducted on a continental scale.” The rabbits who were infected came down with a disease called myxomatosis. This condition quickly killed many rabbits.
Then—perhaps due to how quickly they breed—the rabbits quickly became immune to the myxoma virus. So the scientists started to work on something else.
That something else was the Rabbit Hemorrhagic Disease Virus, or RHDV. In the ‘80s, scientists began to use it—cautiously, in a very controlled manner—to reduce the still-rampaging rabbit population spread. RHDV is an RNA virus transmitted by flies. It kills rabbits 48 hours after initial infection. For a decade or so, the scientists saw slight but promising results.
Then, in 1995, the RHDV virus escaped a quarantine facility, seriously decimating the amount of rabbits in the wild. It was calculated that RHDV lowered rabbit numbers in Australia by 90%. However, rabbits that lived in areas where there weren’t a lot of flies gradually began to develop a resistance to RHDV.
Scientists began to realize that they were seeing a pattern. Evolution and the incredibly fast breeding pattern of rabbits would make it very difficult for any rabbit-specific disease to wipe out the pests entirely before at least some became immune.
So they turned to poison, instead. Using aerial bait drops of a chemical called sodium fluoroacetate, scientists were able to kill off entire colonies of rabbits. Using carbon monoxide and phosphine, they were also able to fumigate underground rabbit warrens—instantly killing any rabbits breeding or burrowing inside.
However, huge chemical drops over large sections of Australia’s wildlife wasn’t good for the environment, either.
Now, Australia’s scientists have several solutions they know sort of work—but we also know that without a perfect solution, rabbits will bounce back more quickly than we can work.
Current rabbit-proofing efforts
Because there’s really no such thing as a perfect solution to get rid of Australia’s rabbits—yet—the current priorities focus a lot on pairing research, physical boundaries, and viral agents to get the best bang for our rabbit proofing buck. For example, current projects include:
- Studying, isolating, and producing more effective RHDV strains.
- Identifying other biocontrol potentials that may work better with less of an ecological impact (such as, possibly, leporid herpesvirus-4, a virus that has recently swept across North America, killing many commercial and pet rabbits).
- Establishing lots of very local Natural Resource Management groups staffed with passionate Australian citizens who have a deep knowledge of their surrounding terrain.
- Helping specific landowners build their own smaller, easier-to-maintain fences, and equipping them with safe types of rabbit poison so they can each protect their own parcels of land.
- Strategically working to support the populations of native rabbit predators, such as feral cats and foxes.
- Locating and destroying rabbit warrens and burrows with poison and fire.
It’s a lot. Here’s a question, though: Has it all been worth it?
We’re going on 120 years of often expensive and sometimes dangerous rabbit management, and we haven’t yet arrived at a solution.
Fortunately, researchers have been monitoring the benefits of the continent’s efforts to curb the rabbit population. Even though they’ve not yet been 100% successful, there have been huge gains. For example, researchers have found that Australia’s agricultural industries saw economic benefits totaling upwards of $43B from 1950-1995 just due to the use of the myxoma virus. The advent of RHDV in 1995 and the use of both biocontrols together saved Australia’s agriculture another $14B through 2011.
We can also see the environmental benefits of rabbit biocontrol. While we haven’t been able to eliminate them over the continent, tiny wildlife preserves where 100% rabbit removal has been accomplished are even flourishing today.
Australia’s rabbit-proof fence may not have worked as well as the government hoped, but it still stands as a first line of defense protecting Australia’s vibrant ecosystems. For now, we watch and we wait, ready for success with a future, less-permeable fence–perhaps, one reliant upon strategic biocontrols and strong community action instead of wire and wood.