The World’s Worst Invasive Mammals

Animals as common as goats, deer, rabbits or mice can have a devastating effect on other wildlife

Long-tailed Macaque (© Arco Images GmbH / Alamy)


(© Paul Harris / Alamy)
Myocastor coypus, or the nutria, is a semi-aquatic rodent originally from South America. Despite their resemblance to rats, nutria were once cultivated for their soft fur. Large groups escaped from fur farms and bred larger feral populations that now inhabit parts of Europe, North America and Asia.

These rodents are accomplished burrowers; their tunnels run through the reed beds and marshlands where they live, eroding river banks and dykes and damaging irrigation facilities. In large numbers, nutria can eat so much vegetation that what began as marshland can quickly turn into open water. In Japan, nutria threaten the critically endangered dragonfly Libellula angelina and the deep-bodied bitterling fish. In Italy, nutria have destroyed the layer of water lilies that once allowed whiskered terns to breed.

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