I know cats (barn cats, ferral cats, house cats) like to eat the heads of prey, at times that's all they eat of the kill.
ub says-
However we all know who really is doing it!!!!!!!!!!!Especially when every single chicken is killed...
I disagree.
How do you know, ub?
When every single chicken is kill in the hen house...it's careful work to determine 'who done it'.
By that, *Mink, Weasel, Cats, Fox, Dog, Coyote and Coon get into a hen house and get on a killing spree.
That predator went for a meal, but it's killing instincts took over when hens had no where to escape and killing was easy.
Yes even a pet Dog. Our son's dog was the guilty party of killing every hen in the coop!
*I have personally caught all the above critters at problem hen houses (and the killing stopped).