Robins at Quabbin

I made a trip over to Winsor Dam at Quabbin Park near dawn. I arrived at 7am with the temperature a cold 5 degrees. I immediately noticed American Robins moving east-southeast in large numbers. My conservative estimate over the next 20 minutes totalled 2460. I missed many as I concentrated on the birds within naked eye view primarily but when I did scan with binoculars there were birds moving along a broad front. I would love to trace the birds back to their roost and get more accurate numbers and perhaps find something odd in among the robins.