The Fox and the Chicken - Part 2

Hello, everyone.  Robin, here.  Rory wanted to make sure that everyone knew that his story was a real event!  It happened yesterday, so we are now down to five chickens instead of six (sniff).  Also, the picture at the top of the post was drawn by Rory in his Nature Journal.  We're now worried that the fox will come back, looking for more chicken dinners.  We're keeping the chickens fenced in, so hopefully it won't get any more.  It was just surprising and a bit disturbing that the fox came into our yard in the middle of the day.  We knew there were foxes around, but the houses where we live are relatively close together.  Our lot is only 1/2 acre.  So, anybody know of a good chicken-and-kid guarding dog?