Somewhat less than a minute. :D And honestly I think they have the size wrong too. While the wild ones are smaller than the domestic, 20 cm is small even for a small female. It's the wrong time of year for it to be a dispersing sub-adult, too, so it has to be an adult unless it was an escapee from a fur farm.

I'm a little puzzled by the local native population just accepting that it's something weird, unless they're looking for something to rook the tourists with. It's not as if they're unfamiliar with mink -- the species is distributed throughout Canada except in the extreme north, and through the entire eastern U.S. as far as Texas. Granted, they're becoming less common due to development wiping out their habitat and prey, but where the do persist they tend not to be shy of people. I've literally walked along a local berm and watched four young mink playing not more than a meter from me. The would stop and eye me every so often, but they didn't try to run away.

I had caught myself on the "big" thing, too. They don't state it, but they clearly imply it, so unless someone stops to think about the actual size it does make the "creature" seem larger than it actually is.