Dan Miller noticed something amiss as soon as he left Park Street station: There wasn't a pigeon in sight. Then he saw something out of the corner of his eye:
... It's a huge gray hawk, its wing span at least three feet. Maybe more.
The hawk settles on the street lamp, looking down at the Tremont Street traffic and the passersby, including me. ...
Miller also explains why it's a good thing he shifted course and didn't walk right under the bird.