The young eastern bluebird was feeling mighty restless. Since hatching in late June and leaving the nest box three weeks later, he had led a busy life. He had perfected flying skills by swooping around the grassy field near his nest in central Minnesota. Like a basketball player practicing layups, he had practiced capturing and eating grasshoppers and other insects until he rarely missed one. As summer wore on, the little bird seemed to always be hungry. He ate so many insects and berries that his weight had almost doubled since August. Now, as days grew shorter and cooler, he felt ready to fly far away from his first home.
Finally, one day, he spread his wings and leaped into the sky. Flapping hard, he climbed higher than he ever had before. Far above his field, he flew into a surprise: a flock of other songbirds, flowing southward like a stream. Joining the flying river, he followed his instinct and his companions.
Flying during the day and resting and eating at night, the flock eventually arrived in southern Missouri. Something inside the young bluebird told him he had arrived at his destination.
Like the bluebird, many birds migrate, flying from one state or country to another when seasons change. Each fall, millions of birds leave for homes hundreds or thousands of miles away. Where do the seasonal migrants go and why? How do they get ready? How do they find the way? Scientists have helped unravel some mysteries of migration—but more remain to be solved.