I have never been attacked by a bird in the wild, but in working with birds in captivity, I've had a couple situations. Once I went into a mew that had a nesting ferruginous hawk. She was very unhappy about that and landed on my back, ripping my shirt and scratching my back. I got out of there ASAP. I also had a time when a bald eagle had gotten tangled into a bungee cord--the cord had actually pierced its wing in a freak accident. It took two people (one of them me) to subdue the bird and put her under. For years I had a scar on my finger where she bit me, but it's gone now. Both of these happened at a rehab center--the hawk was an educational bird and the eagle was a bird that we were attempting to treat and release back to the wild. I volunteered there for a year--it was a great experience.
For wild birds, I would never approach a swan or a heron--just too dangerous.