Corvid cruelty?

So... I've had a week off of blipping! Too many other things going on ... but I'm back :)

What's going on here then? We came across this scene in a fenland field this afternoon ... a corvid trapped in a cage along with a bowl of water and the half-eaten body of a pigeon. Scattered all around were the remains of other birds (also pigeons I think). Is this some strange but accepted fen practice, or something more concerning?