Birds often migrate in the winter months. In order to get to their new destination, migrating birds have to navigate. Many birds fly thousands of kilometers in the winter. Smaller birds like hummingbirds don't fly as far as larger geese and herons. But like many birds, hummingbirds regularly return to the same garden or park each year. Many migrate on the exact same day of the year, leaving their home for warmer regions. Biologists have long been puzzled by how these birds know where to go.