Migratory reflex and navigational skills appear to be written in the
genes. Captive birds have been observed getting pretty fidgety and
changing their sleep patterns right before their natural migration time.
Ethologists—those who study animal behavior call the birds' behavior zugunruhe. Captive birds display zugunruhe even if they're not
exposed to natural light or to seasonal temperature changes. Even with
the restlessness, many of these birds will orient themselves in the
direction that they would normally be traveling at that time of year.
Researchers say that the fact that the birds know both when and where to
migrate without environmental clues suggests that genes, and a
biological calendar written into them, play a role in migration.
