By a tangle of alder roots on the opposite bank of the River Devon, a black-furred scurrying caught my eye.

I knew instantly it was an American mink and brought the creature under the focus of my camera. There was no denying that this animal was a real beauty with a cute weasel-like face, little white chin and lush-furred body. Of course, the flip side is that mink are not native to our shores – they hail from North America – and are descended from fur farm escapees from several decades ago.

As such, the mink creates turmoil upon the fragile river ecology and is universally detested by river managers and conservationists because of the havoc they create upon native wildlife. They will take waterfowl and their chicks and eggs, prey upon trout, young salmon and nesting sandpipers, and can wreak considerable damage upon a sand martin colony.

Mink are also the villains of the peace when it comes to the demise of our water vole populations, which have plummeted by over 90 per cent in recent times. The mink is a consummate predator – it can swim and dive like an otter, and climb trees with the agility of a pine marten.

Mink are unusually bold mammals and will often tolerate the close approach of a person without paying the slightest attention. An animal once literally walked over my feet on the banks of Loch Ness, and I have had other similar encounters over the years.

When I posted one of the photos of my latest mink encounter on my Facebook page, the comments were predictably negative about their presence on the Devon. Whilst I agree with such sentiment, it is important to remember it is not their fault they are here, it is entirely ours, and is just one more example of how we have a capacity to interfere with the natural way of things to the detriment of our environment.

On the positive side, I do not see nowadays as many mink on the River Devon as I have in the past, possibly because of a resurgent otter population, which because of their larger body size, are out-competing this North American invader.