Page 90 - The Miracle of Migration in Animals
P. 90
THE MIRACLE OF MIGRATION IN ANIMALS
Left: The structure of the
magnetic field resembles
that of a coil. Its effect is
strongest at the poles
and weakens towards the
equator. Some birds have
been found to sense this
field, whose existence
people have discovered
only recently. But birds
have perceived this effect
for millions of years and
can easily determine
which way to go when
migrating.
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