I've come across some (quite old) advice that polysulphide sealant isn't liked by birds. Polysulphide's largely fallen out of use now though - any thoughts on magpies and polysulphide's more modern replacements like polyurethane, modified and hybrid polymers and modified silane? (Polysulphide sealant is still available.)
I don't know why they do this - crows and rooks are better known for this kind of behaviour but usually attack rubber seals and wiper blades etc. Any thoughts on the best, magpie unfriendly, alternative to silicone for sealing around PVC frames? (The rubber seals around the glass are ignored by the magpies although they peck the glass occasionally.) Thanks in advance.