While looking up some other material, I happened to come across a surprising note on the IUCN page for Small-clawed Otter saying "Introduced: United Kingdom (Great Britain)". The reference for this was Jefferies, D.J. 1989. The Asian short clawed otter Amblonyx cinerea (Illiger) living wild in Britain. Otters (Earsham) 2(3): 21-25; and Jefferies, D.J. 1991. Another record of an Asian short-clawed otter living free in Oxford with notes on its implications. Journal of the Otter Trust 2(5): 9-12. This took me somewhat by surprise because to my recollection I had never heard of this before. I had a quick google and found the following article from 1996. Asian otters thrive in chilly Oxford river | The Independent Then I found a 2008 pdf entitled "The status of scarce non-native birds and mammals in England" with the following: And thus an interesting tale came to an end. Or do the Small-clawed Otters still live there, and the locals are assuming they are just Common Otters...?