We have twice been called by people who have caught a "black ferret".
The first one had been cornered by a security guard at Walmart who had
chased it with a baseball bat.  It was forturnately not injured and
turned out to be a ranch mink, actually more dark silver than black,
with a small white mark under his chin.  We took it to a wildlife
rehabilitation group and he did quite well.
 
In the second case we had a call from a little girl, aged 8 or 9, who had
caught a "black ferret" in her back yard where there were woods.  It
smelled bad, she said, and so she gave it a bath and was bitten a couple
of times in the process.  When we arrived her father was able to chase it
into a carrier although it was very quick.  I determined that it was a
wild mink and again prevailed upon the wildlife rehab people to care for
it.  Although the little girl's father was pretty upset about the bites
they were able to convince him, and their physician, that it the mink was
not rabid.  (I'm not sure how they managed this.)  So the little guy's
life was spared and he (she?) was returned to the wild.
 
Both of these "black ferrets" were very beautiful but moved differently
from our domestic ferret friends.  They were quick and cautious and
slinky and I am pleased to have encountered them.
 
Bobbi McC., KC Ferret Hotline and Shelter
[Posted in FML issue 4615]