The Magpie antodote:::
Yes, 'tis th season.
The reason why most nasty Maggies are nasty is directly because of negative experiences in the past, which tends to carry on thru the generations (the babies see it and do the same). Sometimes it's someone wearing a red shirt that throws things at them, sometimes it's a bike, a dog, a child, an old person... whatever it is, they are only reacting to the associated negative experience. Some people walk around with a stick, which often attracts their aggresive attentions because they have bad experiences with stoopid agressive stick-waving humans. It's not the magpies, it's US. The magpies at my place eat out of my hand; they don't swoop at ours because they like eating. So do their babies!
There are only really 4 practical approaches to the problem:
1.) avoid them;
2.) stop everyday and leave food in an appropriate place for a couple of weeks;
3.) bang cable ties on yr helm (I ride a large tallbike everyday in Canberra - it works);
4.) paste some eyes on the back of yr helmet. They have to look realistic (ie. proportionally. Doesn't have to in technocolour or anything!); when you look at a Maggie (or if they think you are looking at them), they won't swoop. That's where the other set of eyes comes in handy, as the other adult Maggie will normally come from behind. The trick is getting the eyes to look like eyes.