Most every night through the summer, flocks of hundreds of crows fly over our house, along the jersey Shore. I’m guessing they go to an isolated island in the bay for the night, for the next morning, they can be seen coming back.
You might be correct to believe that, we also have to consider that they might be Fish Crows that usually forage and live and roost in the coastal marshes and landfills. They always fly in large flocks.
H.J. Ruiz - Avian101 
Most every night through the summer, flocks of hundreds of crows fly over our house, along the jersey Shore. I’m guessing they go to an isolated island in the bay for the night, for the next morning, they can be seen coming back.
You might be correct to believe that, we also have to consider that they might be Fish Crows that usually forage and live and roost in the coastal marshes and landfills. They always fly in large flocks.