Crows Vs Magpies

Hi all,

I did try and have a look to see if there a discussion on this already but nothing specific or recent (the chat search here not the best) so hence started this one.

We've watched a pair of magpies diligently build their nest the last few weeks and there seemed to be some egg action at least recently as one remained whilst the other hunter-gathered. This triggered some crow bothering (we all know there little love here between these 2 trouble makers) and after many a kerfuffle today the magpies sat in another tree near looking mournfully (at least in my mind!) at their nest. It seemed clear the crow had the eggs. We know magpies can be vandals themselves but it heartbreaking to see knowing the work gone in plus the trauma to them. Is there any way one can alleviate this? Any solutions? Does a crow-repellant nest exist?! Should we make one with a hole just big enough for the magpies but not the slightly larger crows?! Is there anything crows don't like to ward them off? A certain smell? Cliff Richard's Greatest Hits on repeat?! :-(