Pigeons with a deficient sun compass use the magnetic compass.

Homing pigeons that had never seen the sun before noon could not use the sun compass in the morning; nevertheless they were homeward oriented. When such birds carried magnets, however, they were disoriented, suggesting they were using a magnetic compass. These findings indicate that the magnetic compass is available to pigeons whether or not the sun compass has been established and that the magnetic compass is apparently the first source of compass information.