Page 92 - The Miracle of Migration in Animals
P. 92

THE MIRACLE OF MIGRATION IN ANIMALS

                     Homing pigeons, before leaving their territory,
                 have been observed circling above their home one
                 final time, probably to take another look at the re-

                 gion’s geographical features. In an experimental trial
                 the birds’ forward vision was restricted to one or two
                 meters (a few yards) by the application of opaque
                 contact lenses, yet they still managed to find their
                 way home. For a while, it was assumed that the birds
                 used the position of the Sun to find their way, but
                 when released on a completely overcast winter’s day,
                 they were still able to return home. However, when
                 magnets were attached to their heads powerful
                 enough to drown the world’s magnetic signals, they
                 lost their way. From this, it was deduced that the
                 birds were guided by the Earth’s magnetism, but it is
                 still not fully understood how birds can perceive it.
                 In recent years, very small particles of magnetic ma-
                 terial have been discovered in the pigeons’ skull and
                 neck muscles. 27
                     How birds find their way is a most remarkable

                 mystery, on which a great deal more research will be
                 conducted. Whatever the methods birds may use, its
                 miraculous aspect remains unchanged.
                     If a bird regulates the direction it goes in accord-
                 ing to changes in Earth’s magnetic field, some struc-
                 ture in its body must enable it to measure these
                 changes. This invites certain questions. If a bird does
                 not come into existence together with this system ap-
                 propriate to its needs, have such systems developed
                 by random mutations as the creatures evolve, as the






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