Wednesday, January 14, 2009

Another Example of Feral Cat Eradication Gone Wrong

Designated a World Heritage site in 1997, Macquarie, an island located halfway between Australia and Antarctica, has had a history of nonnative species inhabiting its beautiful landscape. The island is well known for its vast populations of seabirds and elephant seals that migrate there each year to breed, but it seems the feral cats, rabbits, rats, and mice have been receiving the most attention. Over the past 100 years, passing ships have introduced these species to the island and now authorities have been working to remove them. Environmentalists were especially concerned for the native seabirds’ survival, so in 1995, the Parks and Wildlife Service of Tasmania tried to remove most of the feral cats. Unfortunately, this cat-removal project shows the dangers of meddling with an ecosystem and not taking into consideration the in-direct effects of such projects.

(Source: www.subantarcticislands.com/macquarie_island.html)

By removing the cat population, this allowed for the rabbit population to explode, in turn, most of the island’s fragile vegetation that the birds depend on for food and shelter has been destroyed and causing many island slopes to erode. According to Dana Bergstrom, of the Australian Antarctic Division, and her colleagues, removing the cats has “caused environmental devastation that will cost authorities 24 million Australian dollars ($16.2 million) to remedy.” Subsequently, the park service now plans to use technology and poisons that were not available a decade ago to eradicate rabbits, rats, and mice from the island.

Again, this story is another example of why humane, non-lethal methods of animal management should be utilized over total eradication attempts. As more attempts to eradicate one animal population take place, the more we hear about how another animal population quickly flourishes and causes new problems. By implementing sterilization programs (such as TNR for feral cats), there is no sudden large-scale change in an environment to create a sudden reaction, instead an animal population is slowly reduced over time allowing the environment to gradually adjust—nature will find the balance and there will be less casualties.

Other Examples:

Cape May, NJ: feral cats removed causing explosion in skunk population
Amsterdam Island: feral cats removed (to protect ground-nesting birds) causing black rat and house mice populations to increase (they began to prey on ground-nesting birds)

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