What predator killed one of my girls? :'( unpleasant pic in post

[50-45-1]

I see in Ireland you have Stout which is in the weasel or ermine family. You also have pine Marten which is the size of a house cat. You also have red foxes. All of these eat chickens.
The kill looks more like bird of prey however. Hawk or owl. Both of these might only take the head.
Except for the stout The other preditors would have taken more than the head, and would have likely escaped with the whole bird.
I see the racoon has been put on the invasive species list in ireland. So that is another posibility. But a racoon will eat more than the head. They will chew on the head to make the chicken shut up then feast on the chest or breast meat.
Are your birds safely secured at night time?
What ever it was will likely return for another meal.
Trail camera can help show you what is visiting your yard when you are not looking.
Sorry for your loss!

 

[adickenscoop]

Have you tried using the poultry predator identifier tool?

 

[cmom]

If you have a game camera you may want to put it up. Most likely once a bird has been killed the predator will be back.