Start with Macquarie Island, located between New Zealand and Antarctica, and the property of Tasmania. Its surface area is only about 128 square kilometers, so you really have to be careful steering GoogleEarth there: one cursor slip and you’ll splash down into the monotonous stretches of the Southern Ocean. (Try 54 deg 29′ 56.07″ S, 158 deg 56′ 16.68″ E to spy on the Research Station).
So here’s the story line. Macquarie Island was discovered by the Brits in 1810, who went gaga over the seals and penguins (which of course were “harvested” for the usual reasons). In exchange, the sailors gifted the island with rats and mice. Great….
Pretty soon, the introduced rodents started annoying the sailors, so then in 1818 they introduced cats. Great….
Oh, then because the sailors were hungry, in 1878 they introduced rabbits. Great, again….
Proceed to 1960 — apparently the sailors hadn’t been keeping up on their part of the deal because the rabbit population had exploded (what a surprise!) to 130,000 animals. That’s a lot of sailor food!
And all that sailor food was overgrazing the island. So next, in 1968, a rabbit flea was intentionally put on the island, and then 10 years later the Myxoma virus was introduced as a biocontrol. Deadly Myxomatosis was rapidly transmitted via the fleas, and the rabbit population plummeted from 130,000 to about 20,000. Ooh, that sounds like an improvement, doesn’t it?
Except for all those cats — about 2,500 of them. They had been filling in for the sailors by eating all the rabbit meat they could. But deprived of the rabbits, they switched to birdflesh. Remember all the penguins? So the bird populations started dropping.
Next to go, then, were the cats. During 1985 to 2000, the total kitty kill-count reached about 2,000 animals. OK, that hurt (especially if you were a cat), but again normalcy was being approached, right?
Well, no. You see, there will always be some survivors after a plague, and in this spirit the surviving rabbit population (remember the rabbits?) rebounded. And with no kitty cats eating them, the rabbit population once again exceeded 100,000 animals.
That brings us up to today. The rabbits are eating everything. Erosion is rampant. An erosion-abetted landslide slammed into a penguin rookery. Once again, things are screwed up. Koyaanisqatsi!
In response to all this, the government of Australia has committed AU$24 million to simultaneously eliminate the rabbits AND the mice AND the rats. This will be the largest eradication program on an island ever attempted. (Against non-native species that is — humans have already demonstrated skill at eradicating native island species!)
There are two lessons in this:
- It is vastly easier to screw up than it is to do right.
- OK, there’s really only one lesson.
(Image: Royal Penguins on Macqueria Island. Credit: M. Murphy under a Creative Commons license.)