I can't recall off-hand the actual wording you used about the situation
of the dead ferrets.  If I read abuse, neglect, or hoarding in where you
don't think that it exists then necropsies with pathology were (are) in
order.  When necropsies with pathology provide answers they not only
teach us, but they also provide ways to avoid future deaths.  Sadly,
these should be done rather rapidly so it may be too late on those 8 (10?)
whom you said had already died and the dead birds.
 
If you do think that there is hoarding, neglect and/or abuse going on
then you know what you need to try to do.
[Posted in FML issue 3783]