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Invaders and Extinction

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Invasive rats have pressured many other species. In the Caribbean alone, the black or ship rat (Rattus rattus) and the Norway rat (Rattus norvegicus) were implicated in the extinction of two native shrew-like mammals from the Nesophontes genera. (Seidel and Franz, 1994).

In the US, invasive alien species are already the most common reason — although not usually the only reason — for listing an organism as officially protected under the US Endangered Species Act: between 35-43% of all listed organisms are under pressure from invasives. Worldwide, according to a recent comprehensive survey, nearly 20% of the endangered vertebrate species are already under threat by invasive species — particularly on islands.

After habitat loss, invasive species are regarded as the second most important cause of species endangerment on a global scale.


References
» McNeely, J.A. (Ed.). (2001). The Great Reshuffling: Human Dimensions of Alien Invasive Species. Gland, Switzerland: IUCN.
 
» Seidel, M.E. and Franz, R. (1994). Amphibians and reptiles (exclusive of marine turtles) of the Cayman Islands. In M. A. Brunt and J. E. Davies (Eds.), The Cayman Islands: natural history and biogeography (pp. 407-434). The Netherlands: Kluwer Academic Publishers.

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