Ah, nesting birds. About this time a couple of years ago I walked to/from work (Chicago) and would cross the bridge on North Ave that went over the Chicago river. There was this bird that would swoop down and peck people on the head as they'd walk by.
The first time it happened to me, I wasn't even sure what happened! So then I turned around and watched people surprise attacked, their arms flailing and yelling, it was that bird! ...sounds scary but it was hysterical!

It lasted a few weeks, I just walked with an umbrella over my head across the bridge. People learned - others had umbrellas, hoods, plastic bags...