To transport a message, a carrier pigeon must be taken from its home loft to the release location, where it is held until it is needed. The message is attached to a rolled-up note in a container on the bird's foot or back. Once released, it flies directly back to its home loft, where the message it carries can be received. A complete explanation of the homing ability of carrier pigeons has yet to be found. Scientists believe that carrier pigeons, like migratory birds, can use the position of the sun and stars as well as the Earth's magnetic field as a compass, and they also utilize visual cues for navigation. How carrier pigeons and migratory birds orient themselves on their sometimes thousands-of-kilometers-long journeys remains an unsolved mystery.