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University of Auckland
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Monday, 17 December 2007 |
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Removing introduced predators in an effort to save rare species can potentially cause a faster destruction of the species, research has shown.
A study by University of Auckland ecology PhD student Matt Rayner and colleagues showed where several introduced animals prey on a native species, the removal of one of these predators may shift the balance of the foodweb such that hunting and destruction of the native species increases.
The research is published in the 11 December online issue of the prestigious journal Proceedings of the National Academy of Science.
On Little Barrier Island, feral cats were removed in 1980 and Pacific rats were eradicated in 2004. Both cats and rats preyed upon Cook’s petrel, an endangered burrowing seabird, however cats also eat rats. Analysis of petrel breeding success data from three sites on the island showed that at higher altitudes, the removal of cats caused the number of Cook’s petrel chicks successfully leaving the nest to drop as a result of increased rat predation. The subsequent eradication of the rats several decades later resulted in the petrels producing more offspring than they had when both predator species roamed the island. By contrast, numbers in the nesting sites at low altitude were not greatly affected when rats were removed, possibly due to the availability of alternate food sources lower down the slopes.
"New Zealand is a world leader in creating safe island havens for threatened wildlife through the control and removal of introduced predators" says Mr Rayner. "However, this study shows that ecological interactions between introduced and native species can be complex and detailed understanding is needed to prevent unforeseen and negative outcomes of conservation management strategies.
Editor's Note:
Original news release can be found here.
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