This book introduces readers to the science behind migration. Students learn about the hunger and nesting factors that motivate birds to fly south for the winter and north for the summer. Vivid photographs and easy-to-read text aid comprehension for early readers. Features include a table of contents, an infographic, fun facts, Making Connections questions, a glossary, and an index. QR Codes in the book give readers access to book-specific resources to further their learning. Aligned to Common Core Standards and correlated to state standards. Cody Koala is an imprint of Pop!, a division of ABDO.