Description Based on the highly-acclaimed National Geographic Channel special, these high-interest readers blend amazing images with incredible stories of the perilous journeys some animals must take in order to survive, inviting readers to follow the fascinating migration paths of some of nature's most driven creatures, including butterflies, whales, elephants, zebras and others. Level 3 readers are perfect for kids who are reading on their own and are ready for a more challenging vocabulary and richer text.