So, as I said in yesterday’s blog, the rabbit-plague solution Louis Pasteur proposed in hopes of winning a million-dollar prize didn’t work and his nephew didn’t wind up with Sarah Barnhart, either. Worse yet, the rabbits kept rabbitting on.
Reports about the 150th anniversary year of the 25 bunnnies originally being set loose here are reminders of why Australian customs regulations are so tight. From experience, actually from scores of bad experiences, Australians know the harm that can come from introduced species.
Another biological solution was proposed in 1919, a disease called myxomatosis. After initial rejections of the whole idea, safety tests, and trials, the disease was introduced to the wild rabbit population in 1950. Spread by mosquitoes and fleas, myxomatosis wiped out 99% of Australia’s wild rabbits in two years.
That is considered to be the world’s first successful biological control program of a mammalian pest.
Of course the remaining one percent of 600 million rabbits is still quite a few, and within a few years, both the disease and the rabbits changed enough so the rabbit problem began to grow again.
In 1995, rabbit haemorraghic disease virus (RHDV) was introduced and once again the rabbit population was reduced to low levels, although RHDV seems to be a better killer of rabbits living in arid areas than of those in high rainfall areas.
RHDV is considered only the second successful control of a mammalian pest in the world. Plant species absent for nearly a century and a half are making a comeback in some parts of Australia now. Feral foxes, dependent on rabbits, have diminished in number, too.
Rabbit numbers at one section of the Flinders Range of South Australia have been shown to be only 15% of their pre-RHDV population level, but we heard a scientist being interviewed on ABC radio recently saying that there are still enough rabbits around to derail plans for planting trees as part of a carbon-emissions control program.
A rabbit or two per square kilometer — a population that might go largely unnoticed by humans living in the area — would be enough to nibble off the tree seedlings, he said. According to him, you can look at wild-tree populations in the outback and see trees that came out of the ground soon after the rabbit-free period of the 1950s and others that sprung up after 1995, but few or none in between. Or since.
Of course, there are bunny defenders. Getting rid of the rabbits hurt hunters (including professional rabbit hunters who were shrewd enough to report areas as being cleared of rabbits while they carefully left a few alive so they’d have more work later), rabbit-fur sellers, and hat makers who used rabbit fur.
Children, of course, worry about harm to the Easter Bunny, so Australia has a government-backed campaign promoting the Easter Bilby, a cute little native marsupial with a long nose, as a substitute that competes for the affections of Aussie young folk. You can see guys in bilby suits on floats in parades and there are children’s’ books and films about the cute little bilbies.
That makes sense, in a way. Rabbits destroy bilby habitat.
Even when we get rid of the bunnies, if we do, there’ll still be other feral invaders to worry about, including camels, starlings, and mosquito fish, red-eared slider tortoises, and something called “the yellow crazy ant.”
Not to mention, of course, the poisonous, ever-spreading cane toad which is moving steadily west across the tropical areas to our north, wrecking havoc as they go. They even kill crocodiles.
The crocs have to eat them, of course, but these native critters seem willing to dine on most anything that moves. Two were found alongside Brisbane-area highways recently (yikes!), hundreds of miles below their natural habitat’s southern limit. Authorities speculated that they were pets that had been set free.
Pets! Who’d keep a croc as a pet? And why?
Even if you could teach one to fetch…
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