My sympathies go to your son & his roommate!  I have ferrets & birds and
never may the two meet.  A ferret will kill a bird - it is natural instinct.
I hope your son's friend won't hold it against him, because the ferret was
only doing what comes naturally, unfortunatly.  A very big part of me would
die if my parrot did, so we always have to be very careful to insure against
that possibility.  Your son couldn't be to blame unless he let them both out
together, and it doesn't sound like that is the case at all.  NEITHER animal
was monitered.  It just happened.
[Posted in FML issue 1591]