Between 12 and 20 billion birds migrate out of North America every year for winter destinations in Mexico, Central America and South America. Songbirds such as warblers, vireos, thrushes and flycatchers are leaving now from their breeding grounds in British Columbia for points south. Most of our songbirds stay the winter in the highlands of Mexico but some such as Barn Swallows and Cliff Swallows will not stop until they reach the Amazon River basin.