For thousands of years, homing pigeons were the most
sophisticated means of long-distance communication. The winners of the
first Olympics were announced by homing pigeon. Julius Reuter started
his news service with them. Cher Ami, an avian member of the U.S. Army
Signal Corps, received the Croix de Guerre in World War I after
completing a mission with a bullet in his breast.
How do the birds find their way home? Decades of studies with frosted
lenses, magnetic coils or scent deprivation show they use pretty much
every clue available. The most difficult one for us to comprehend may be
the earth’s magnetic field. Birds see it, but what it looks like to
them, nobody knows. Work by Roswitha and Wolfgang Wiltschko in Germany,
among others, suggests that this sense relies on quantum mechanics—that
is, birds detect something happening in the eye at a subatomic level.
Light striking the retina seems to stimulate chemical reactions that
produce pairs of molecules with electrons that are “entangled,” meaning
they share certain quantum properties. One of those properties, called
“spin,” is affected by a magnetic field. That effect could tell the bird
which way is north.
Charles Walcott of Cornell, who began studying pigeons in the 1960s,
says homing is “still a mystery”—a reminder that “it’s a mistake to
think that we live in the same sensory world as other animals.”
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