A caged bird's escape attempts pointed straight at the North Star
In the 1960s, Stephen Emlen raised indigo buntings in a planetarium and placed them in ink-blotting funnels that recorded which direction they hopped toward as migration season approached. The birds consistently oriented toward their migratory direction based on the night sky, and when Emlen rotated the projected stars around a different 'north,' the birds recalibrated and followed the fake pole instead.