...but!
They're clever wotsits, and make themselves scarce every time the nice (shotgun) man from the village comes along in his little white van -
Chatted to the local vet today who confirmed that magpies _love_ rat-bait.... so that's a non-starter.....
There was a posting on the web about feeding them bicarb (seagulls, specifically) which apparently has interesting results.
Generally, we like wildlife - but magpies!
Adrian