A secure coop is really the only way to keep them safe. Mink and weasels can walk through most fences, raccoons and fishers can pull them through. If the fenced in area isn't covered then you have owls, and fishers can climb very well too. If the fence isn't tall foxes, coyotes and bobcats can jump over the top.Are her chickens safe? What safe-guards does she use?
About all I can do for mine right now is to lock them in the coop but it wasn't meant to hold about 80-90 chickens, guineas, ducks and geese. I had hoped the little ones, bantam Cochins and others as small as they, would be safe in a pen right next to our front porch but he pulled one out through the fence, and the light was on!!