Tree Swallows swirl down to roost!

Each winter millions of Tree Swallows migrate south from their boreal breeding grounds where they take up residence in the southern United States. The Tree Swallows form massive roosts and show a high fidelity to these sites until the sugar cane fields are harvested. This video clip shows the evening masses building and finally becoming a wild torrent of birds spreading across the sugar cane field. This particular roost has been estimated to hold more than 4 million birds.