We had a terrible mouse problem in our first home.  It was a converted lake
house and had holes everywhere!  It was so bad that the little buggers were
having litters in my dresser drawer.  We then got the ferrets.  The mice
vanished.  As far as I know the ferrets never caught the mice.  When we
first moved to our present home, one of these original ferrets was still
alive.  Mind you, she was 9 and not running around much at all.  About a
year after she died the mice invaded.  They were running all over the
basement and pooping in the silverware drawer.  We brought Sugar home and
the mice vanished.  Again, as far as we know none of our current fuzzballs
have ever caught anything.  We also had 3 cats at the time, none of which
prevented the mouse takeover, although they occasionally caught them.  I
would suggest the poop or bedding idea.  Our ferrets have never been in
the basement and the mice appear to be gone.
 
Just our experience, nothing scientific.   Good luck!!
 
Jean
[Posted in FML issue 2682]