I know hen harriers are beautiful, but that does not mean what eats them should be destroyed.
These species coexist in the mainland, in Scotland hen harriers live alongside golden eagles which are much more powerful birds, eagle owls are not going to track down specifically hen harriers on purpose. So one owl attacked a hen harrier. Big deal- this owl is never going to wipe out all hen harriers in the UK.
However, it is a native species, and its extinction date has been determined as 2,000 years ago. For comparison the lynx vanished 1,300 years ago and the stork 604 years ago. It is definitely a native species, and the problem I think people have with it is hen harriers, though that in no way should be a reason to even limit their spread. This is one example of if something rare and beautiful is being killed people get enraged at the perpetrator which is a simple and beautiful owl which is NATIVE and actually could help deal with the massive roe deer problem. Capercaillie is almost gone as well- should we get rid of golden eagles as well? Montagu's harrier is almost gone- should we get rid of what preys on them as well?
Nothing I have seen on this thread makes me seriously think their spread should be stopped. I love the RSPB- they preach about protecting birds yet want to wipe out a native species. All because of a flappy bird which is beautiful.