It starts around late winter/early spring, but I would like to know when it ends so I can resume my daily walks.
(I have a fear of magpies, lol)
Their breeding season varies a lot. Sometimes it can be between June & September. Other times it doesn't start until September & may go through to January if your in a cooler area.
In my area they have been breeding around June, July & had a break. Now they're breeding again ...
It is the males that swoop to protect their young.
It varies. Usually by the end of December.
I got followed by one only a few hours ago while cycling. He didn't swoop me but he had his eye on me and made a bit of a noise lol.