NITE GUARD or NITE EYES - These devices work!  I can't tell you why, it doesn't seem they would work, but the DO! 
For instance, we have lost two, 4 bird flocks, one by one, to a fox - actually two foxes (I couldn't believe it when I saw TWO!).  Always when they were free ranging (of course).  So I decided to try something new.  NITE GUARD is the one I have.  It's a little black box with a blinking red light in the center.  The red light makes predators think it's another predator and they stay away.???  Don't ask me why it works, it just DOES!
I bought two and mounted them diagonally on each opposite corner of the run/coop sometime in early fall.  All fall and winter the little red light flashed and all winter long (in Maine here!) we never saw ONE foot print from ANY predators and best of all we haven't lost any since!
They suggest you buy four, of course, at around $20.00 each.  I only bought two as I said, and mounted them at two opposite corners.  Works for me, and others so I have read.  Check it out on-line.  So sorry to hear about your losses and good luck with your new babies!  So cute~!