It's a probably a red winged blackbird and this is a somewhat seasonal response and not all that uncommon. I like the idea of creepy eye like stickers on the helmet, though that may just give the bird a target. If you're wearing a helmet and sunglasses there's little chance the bird will do you any real harm. I'd relax and enjoy the attention and it certainly gives you a good story to tell.

Catch some video of it and post it on youtube- I'm sure lots of people would delight in your suffering.