I want to know the answer to the following question:
What do caged birds display that corresponds with migratory direction in nature?
All the background I'm provided with is that "The occurrence of Zugunruhe even in cage-raised birds with no environmental cues (e.g. shortening of day and falling temperature) has pointed to the role of circannual endogenous programs in controlling bird migrations.". Is that enough to answer the question?
Answer: no