Page 48 - The Miracle of Migration in Animals

THE MIRACLE OF MIGRATION IN ANIMALS

Why Do Most Birds Migrate at Night?

Birds conduct most of their activities during the day, but choose
to make long journeys at night. Shorebirds and small birds like fly-
catchers, golden orioles, most kinds of sparrow, warblers and field-
fares are classic night migrators. At night, there is a surprising lot of

activity in the sky. A telescope aimed at the sky during a full Moon
observed an estimated 9,000 birds per hour passing by. These night
migrations begin one hour after sunset, peak just before midnight,
and fall off towards daybreak.
Birds’ nocturnal migration is advantageous in a number of
ways. Most importantly, in this way they can evade their enemies
like hawks and falcons. A large number of migrating species are
small and have weak flying capacity, so it is safer for these birds to
fly in the dark. But night migration is not just for safety alone, for
some coastal birds—powerful fliers that can go over the ocean non-
stop for 3,200 kilometers (2,000 miles)—also migrate at night.
Another reason why birds choose night for travel is that birds
feeding during the day usually have a very rapid digestion.
Consequently, they have to eat at short intervals, and these calories

must be deposited in their body in the form of fat. Were small migra-
tors to make long flights during the day, they would be exhausted on
arriving at their destination, and since they cannot forage at night,
they would have to wait until the next morning. As a result of being
unable to obtain energy, many would probably be unable to survive
in a cold environment. For this reason, these creatures act in a very
programmed fashion, feeding by day and migrating at night, resting
at sunrise and continuing on in this cycle.
Although this has not been proven, one advantage of traveling

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