Swarms of Swallows 

Plum Island, Massachusetts

   The annual gathering of tree swallows on Plum Island, Massachusetts, peaks in late August and is spectacular to watch. A key stop on the eastern migration route, thousands upon thousands gather, feasting on the island's ample supply of bayberries to shore up energy for their journey south.

     With an ebb and flow that seems to pick up pace throughout the day, dense flocks rise from the thicket in swirling arrays and settle back into the landscape.

     A tree swallow's usual diet consists of flying insects, but the bayberry seeds they find on the island offer a highly concentrated source of energy, and tree swallows are one of the few birds able to digest the waxy fruit that covers the seeds. They will also eat winterberry and viburnum along their route. 

     During breeding months, tree swallows are found throughout the United States and Canada. Wintering grounds for these northeastern migrators typically range from Florida to Central America. In March they will return to the Northeast as welcome harbingers of Spring.