The annual Old Saybrook swallow spectacle is in full swing. Each fall, the skies over the Connecticut River fill with hundreds of thousands of migrating tree swallows as they circle before roosting for the night on reedy island in the river. Here, Linda and Alex Calvo and Marilyn and Jeff watch the birds arrive on Sept. 23 on the Essex Steam Train’s River Boat Becky Thatcher as part of the Connecticut Audubon Society EcoTravel Swallow Boat Cruise.