My girls play *very* rough.  The only reason I realized that it was play
and not fighting is because they lived together prior to going to the
shelter that I got them from.  They love rough play.  They pounce on each
other from behind.  They grab each others necks.  Sometimes when the skin
is in their mouth they'll shake it like a dog shakes its toy or drag the
other around a short distance.  But typically after this display, the other
will jump around and try to do the same.  It's just how my girls play.
Other ferrets may not understand.  When one of mine tried to play that
way with another ferret, the ferret freaked out and screamed and ran away.
 
That's not to say that they don't fight other ferrets.  When we added
another ferret to our home, there was a subtle difference in her behavior
when she did the neck biting.  It was *way* more aggressive.  She was on
a mission and there was no weasel war dances afterward.  It was more like
constant striking at the new one.  One of the things that I read somewhere
is that if the one being bitten jumps around and goes back for more, then
it's play...
 
Hope this helps,
Suzanna
[Posted in FML issue 3473]