I am assuming where there is one fox there is probably more, I am not sure how much one fox eats but I really dont think it was just one animal chances are others heard that there was a free buffet and came running (sorry I am not trying to be cruel, just, well you know everything loves chicken)
I lost my first set of chooks to all the creatures of the night once when an animal penetrated what I thought was a secure run, and that particular night I was sick and did not lock them into the totally secure (with out a doubt) coop. all that was left of 6 birds ws feathers and feat. they were just about to begin laying too, it was a huge set back. We learn from our mistakes at least we try to so that they serve some purpose, I think almost all of us have been in your shoes in one way or anothe