I was driving and saw the same thing and heard someone comment about the birds.  Unfortunately, due to the traffic, I was unable to turn around and take a look.

I was a volunteer with them the last 4 years and would have been again if I were still there. I've had to settle for following the daily emails. (Hawk Ridge website would have the link.) It's a great mingling experience when they're set up in Lake Place Park with everyone from kids to homeless to downtown workers to tourists following the nest box events.