View additional resources, online and in print, for NATURE's "Flight School."

Joseph Duff is one of the leaders of Operation Migration, a nonprofit organization that is using aircraft to restore migrating populations of whooping cranes.

In the 1930s, a young Austrian scientist named Konrad Zacharias Lorenz formally documented the process of "imprinting" -- socially bonding to a parent figure.

Each spring and fall billions of birds hit the "flyways," atmospheric roads for annual migrations, which can stretch thousands of miles.

To help ensure the survival of endangered whooping cranes, Operation Migration maintains an artificial breeding program that prepares chicks for adulthood.