Saturday, January 31, 2009

Cats and Rabbits and Aussies: Oh My!

One would think after their disastrous attempts to solve their pest problems by introducing cane toads to their continent (and producing an additional whopper of a pest), the Aussies would be a little more careful the next time they attempted to assist an environment. No such luck:

"It seemed like a good idea at the time: Remove all the feral cats from a famous Australian island to save the native seabirds.

But the decision to eradicate the felines from Macquarie island allowed the rabbit population to explode and, in turn, destroy much of its fragile vegetation that birds depend on for cover, researchers said Tuesday.

Removing the cats from Macquarie "caused environmental devastation" that will cost authorities 24 million Australian dollars ($16.2 million) to remedy, Dana Bergstrom of the Australian Antarctic Division and her colleagues wrote in the British Ecological Society's Journal of Applied Ecology.

"Our study shows that between 2000 and 2007, there has been widespread ecosystem devastation and decades of conservation effort compromised," Bergstrom said in a statement.

The unintended consequences of the cat-removal project show the dangers of meddling with an ecosystem — even with the best of intentions — without thinking long and hard, the study said.

"The lessons for conservation agencies globally is that interventions should be comprehensive, and include risk assessments to explicitly consider and plan for indirect effects, or face substantial subsequent costs," Bergstrom said.

Several conservation groups including the International Union for Conservation of Nature and Birds Australia said the problem was not the original eradication effort itself — but that it didn't go far enough. They said the project should have taken aim at all the invasive mammals on the island at once.

"What was wrong was that the rabbits were not eradicated at the same time as the cats," University of Auckland Prof. Mick Clout, who also is a member of the Union's invasive species specialist group. "It would have been ideal if the cats and rabbits were eradicated at the same time, or the rabbits first and the cats subsequently."

I would like to see some comments to this effect made prior to the eradication effort. It is entirely too easy to say in hindsight "we should have taken the rabbits too". Has there been a thorough analysis of what would have happened if they had done so? Perhaps there are species there that depend on both the rabbits and the cats in some fashion. Nature and the creatures in it are interlaced in highly complicated ways that we are only beginning to understand.

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