Nat Geo Readers Great Migrations ButterfliesNational Geographic Readers: Great Migrations Butterflies by Laura Marsh. This special series of NG Readers will serve as companions to the 10-hour National Geographic special, ""Great Migrations."" These specially branded books will combine the powerhouse that has become the readers audience as well as the huge audience of animal lovers that will be following the television series. In a world of changing global temperatures both on land and in the sea, the annual migrations of animals include amazing stories of incredible strength and the will to survive. New technology for tracking animals is helping us to understand the world in constant motion. This journey follows the monarch butterfly as it makes it's cross-continent migration south.