At about 4:45 pm I raised the shades at my window at work on Shelburne Rd, and noticed a steady stream of crows flying from the farm fields, across the intersection of Shelburne Rd and Bay Rd. I don't know when the flight started, but I watched for 15 minutes, during which at times I couldn't keep up with the flow but I'd say a reasonable estimate of peak flow was approx 700 crows per minute for a duration of 2 minutes, with a more typical flow of 300 crows per minute.
The flow ended fairly quickly, so I'm guessing that there are approx. 5,000-6,000 crows roosting somewhere near Shelburne Bay tonight, possibly down below the Automaster.
It was a very nice way to watch nightfall.