Another blog that I follow has been discussing the actions of a pair of hawks in New York City as they appear to be building a new nest. According to that blog hawks often stick to one nest though they might build a secondary nest before laying eggs. These birders aren't sure why, but think the reason may be to give the female a choice or just as a bonding ritual. Sometimes the pair will desert the first nest in favor of the second. Very soon it will be time for our hawks to be nesting if not already. This hawk was very busy flying away from the nest and back. While I didn't see it carrying any twigs, that may be what was going on.
The hawk seems to be observing me as I observe it. I don't stay long and soon head to the store to refill my own nest.