I was very surprised how bold these birds were, but they've obviously become calm around people at this particular park, and they were foraging in the picnic area, so it's likely some visitors give them food (no one there at the time was eating anything).  I was standing with my camera out in the open, as was my friend, standing very still, and they were coming this close to us!  A few other people were there, too, watching them.  :)