Right thanks mrs o. The reason I ask is that last spring I watched a pair of magpies build a nest in a tree opersite our house and I have noticed a pair of magpies seem to be taking interest in the same nest right now.
The pair I see are deffo in the same tree but I cannot swear it is the same nest. I cannot see why they would build another nest in the same tree if they already have one
Don't see any where we are now, before we moved there was a nest across the track from us that was used for at least 4 years on the trot, it just kept getting bigger.
I'm pretty sure they may often use the same nest several years running.
I read somewhere that in recent years, some have started to build 'domed' nests, as opposed to open topped. Being adaptable, I think is part of their success