What is killing my hens?

[Merax]

So was it the rooster? Seems really unlikely that a rooster would kill a hen from his own flock.

 

[dmanhefner]

What you are describing with your rooster is chicken love, normal behavior with young rooster, he will get better at it and the hens will get used to it. Your predator is an owl or a hawk since it was by a post and you have an open top. They also go for the neck and head first. Cat just found a free dinner.