Sorry that happened Bigfoot They are bad, we have lost a few calves to them over the years, We try to make them know they are not welcome, but it's impossible to be close by all the time.
@BFE when I had sheep, I had Great Pyrenees, the male dog would not even let a blackbird land in the field. The problem is that the dogs love to roam and it's about impossible or it was for me to keep them in where they need to be. We have a female Blue Heeler thats always on guard for anything be it walking or flying around the yard. She will see buzzards or hawks flying and run after them barking and growling.