they're too much like the old legend of the 'black shuck' which is little mroe then folk superstition for my perosnal tastes.

I think a few sightings of large escaped cats (they're are apprently 10 believed colonies of escaped big cats, alhtough these are totally unsubstantied, coupled with the old folk mythos and the effects of feral dogs and even more adventurous Foxes.

I think that they're could be escaped big cats, but they're not a problem. However as they're not indigenous I would advise against letitng them be, if you want an example look at what happened to the indigeonous red squirral after the introduction of the American grey.

Neon