How Do Courier Birds Know Where to Go?

At the start of every Olympic Games, doves are released to commemorate the earliest Olympic competitions, when pigeons carried the results to distant lands. The bird courier practice began as early as 400 B.C. and continued until 2004, when India retired the last of the world's pigeon couriers. No one knows for sure how pigeons -- or doves -- always make it home, but a few theories exist.

  1. The 400-Mile Journey, In Two Legs

    • A modern-day racing pigeon can fly roughly 400 miles in a single day, often at speeds of up to 50 miles per hour. During the first 360 miles of the journey, the pigeon's "instincts" -- possibly a geomagnetic or solar sensitivity, although no one knows for sure -- guide it home to the roost, or the finish line. Pigeons use visual cues, such as buildings and towers, to complete the final 40 miles of the journey.

    Geomagnetic and Solar Activity

    • A pigeon's reaction to the Earth's magnetic and solar forces may explain its instinctual homing skills, but no hard evidence exists to prove the phenomenon. However, pigeons become disoriented during geomagnetic storms, which are caused by a sudden shift of energy on the sun, or a coronal mass ejection. During these CMEs, pigeons lose their navigational skills and may never return home. For this reason, pigeon racers -- or fanciers -- monitor electromagnetic forces during each leg of the competition. In the United States, the Space Environment Center in Boulder, Colo., provides free geometric readings to pigeon fanciers.

    Atmospheric Infrasounds

    • On June 29, 1997, 60,000 racing pigeons took to the skies in a 400- to 500-mile race across the English Channel, but only a few made it home. As most of the faster birds were flying over the Channel, an international Concorde flight intersected the race route, creating a sonic boom. Only birds that were south of the Channel completed the race, leading scientists to postulate that pigeons rely on atmospheric infrasound -- low-frequency sounds caused by slight changes in the Earth's movement -- for navigation.

    Highways and Roads

    • During the final, 40-mile leg of a 400-mile journey, pigeons sometimes use highways for navigation. A 2004 Oxford study confirmed that carrier birds may even follow the highway directly, taking a specific road junction as they fly. Even more interestingly, the pigeons in the study followed the highway even when "as the crow flies" short cuts were available. Researchers concluded that pigeons may value roads more than energy- or time-saving measures.