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The Closest Thing to a Silver Bullet in Conservation?

The rats, goats, dogs, cats and other mammals that spread round the world with humans have driven many native species to extinction. New research indicates that clearing invasive species from islands might be the closest thing to a silver bullet in conservation.

For example, Lord Howe Island in Australia has finished eradicating the entirety of their invasive rat and mouse populations, and the recovery of the endemic-Australian ecosystem has been near-immediate. It's a conservation success story that's being emulated around the globe.

Islands are home to some of the strangest and most charismatic life on Earth. Lemurs, giant tortoises and wombats are among thousands of species found nowhere else but their native archipelago or islet, the result of generations spent evolving in isolation away from the mainland.

On Gough Island in the south Atlantic, invasive mice killed roughly two million seabird chicks every year according to a 2018 study, devouring endangered albatrosses and prions alive in their nests.

Such interactions mean that while islands are just 5 percent of Earth’s land area, scientists believe they have been home to 60 percent of all global extinctions since the 1500s. But there is hope – and a lot of it.

New research indicates that clearing rats, mice and other invasive species from islands might be the closest thing to a silver bullet in conservation. From the Galápagos to the Palmyra Atoll, analysis of nearly 1,000 eradication programmes since 1872 found that they had almost a 90 percent success rate. The subsequent transformations have been striking, says Patrick Greenfield in The Guardian.

On Redonda island in the Caribbean, where invasive goats had overgrazed plants so much that they were starving to death, their removal – along with black rats – has seen the return of trees to the island which resembled a moonscape before the eradication efforts. On the Palmyra Atoll in the mid-Pacific, coral in the lagoon has rebounded, native plant seedling have increased by over 5,000 percent and crabs are recovering after rats were exterminated in 2011.

The research indicates that the scale and complexity of invasive species eradication programmes is growing, and with it, a real chance to undo some of the damage humans have done to islands ecosystems around the world.

Places like the Galápagos, Madagascar and Borneo are famous havens for biodiversity, and removing invasive species can ensure their survival in a heating world. Countries such as New Zealand, which has no native land mammals apart from bats, has a target of clearing all invasive mammals by the middle of the century.

“This is probably one of the most effective conservation tools that we have in our hands for protecting our biodiversity,” says Piero Genovesi, a leading expert on invasive species and co-author on the study. “We could definitely improve the status of many threatened species if we only apply that eradication more widely in the future.”

Lord Howe Island panorama

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