Removing Cats to Save Birds Causes Bird-Killing Bunny Explosion

The decision to remove feral cats from Macquarie Island, located halfway between Australia and Antarctica, has proven to be a bit of a mistake. Researchers say the attempt to protect native seabirds was well intentioned, but had an unexpected consequence: allowing the rabbit population to explode which in turn destroyed much of the vegetation the birds depend on for cover.

Removing the feral cats from Macquarie Island has caused ecological devastation that will cost Australian authorities AU $24 million (US $16 million) to fix.

From MSNBC:

“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 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.

Located about halfway between Australia and Antarctica, Macquarie was designated a World Heritage site in 1997 as the world’s only island composed entirely of oceanic crust. It is known for its wind-swept landscape, and about 3.5 million seabirds and 80,000 elephant seals migrate there each year to breed.

The cats, rabbits, rats, mice and other nonnative species currently inhabiting the island were likely introduced by passing ships over the last 100 years, and researchers have long been trying to get rid of them. In 1995, the Parks and Wildlife Service of Tasmania began trapping the cats to protect threatened species of native birds.

Efforts to eradicate non-native species have been successful on other islands, but only when a more all-encompassing tactic was used. Professor Mick Clout of the University of Auckland says the Parks Service should have removed both the rabbits and cats at the same time. A spokeswoman of the Parks Service said they were aware of the risk that the rabbit population would increase but thought it was worth it to avoid further damage by the cats.

This is what happens when you mess with ecology. Unfortunately, the next step the Parks and Wildlife Service plans to take is to use poisonous bait that targets pest animals on the island. This, too, seems like it could have unintended consequences. Of course, something must be done to protect the birds, though, so we can only hope that future efforts to save them are more successful without causing further damage to the island.

Link [MSNBC]
Photo credit: ABC News

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