It would be more effective killing the females, I've had a look underneath
the
last ones I've disposed of, and there was a smal projection about a third of
the
way up the body on some of them but the last one did not appear to have this
projection, is that the difference?

Alan

Ith the projection is a penis, I think you've found your 'difference', though I
doubt you'd be able to get close enough to any squirrel to 'lift its skirt' to
be able to tell the difference before you decided whether you were going to
dispatch it or not.

;o)

Dave.