FFS,
The fox itself is a predator that will kill for the sake of killing and not just to eat
Nope wrong and annoying to see this lack of understanding still going on,
Imagine you were in the middle of the Canadian wilderness, living in a cave with your children, having to find your own food,
you are wandering through the woods, and you come across a gaggle of geese, you manage to trap them in a gully,
You kill one, but they are huge, and you will only be able to carry one back to the cave, do you;
A. kill one and let the rest go.
B. kill them all and go back and forth to carry them back to the cave, and have food for the next week.
C. kill one, take it back, come back and hope to find the others to kill.
If you find a fox has killed all your poultry, if you do not disturb the scene or the fox you will see it come back and take one after the other, every single time,
When people make statements about animal behaviour it worth remembering, it is never illogical , if you don't understand why an animal is doing something watch more carefully, eventually you will work it out, but making up answer is silly, or look it up.