If we didn't have the knowledge acquired over centuries by ornithologists and naturalists, how would we explain where migratory birds go in the autumn? Here are some theories from antiquity accounting for bird migration.
Birds Fly to the Moon for the Winter
Many birds fly at high altitudes while they migrate-Bar-headed Geese cross the Himalayas at 9,000 metres (29,500 feet)-far out of sight of human observers on the ground. The ascent of migrating birds in the fall, apparently headed into space, probably inspired the belief in the Middle Ages that they went to the moon for the winter.
Birds Changing into Something Else
Atlantic Puffins have brightly coloured bills only in the breeding season; the Piping Plover loses the black on its head and chest in winter; in many species, the male, female and juveniles look quite different from each other. This type of physical variability in birds proves that they can change their appearance and made it logical to early philosophers and scientists that a bird absent in winter had simply changed into something else. Sophocles thought that the Hoopoe and the hawk were the same bird (Ingersoll, p. 92), and others believed that the Cuckoos and Sparrow Hawks were the same species (Ingersoll, p. 93).
Little Birds Riding on Big Birds
Many people once thought that small birds migrated by riding on larger birds. Ernest Ingersoll writes that, in the late 1800s, Egyptians believed that storks and cranes carried wagtails across the Mediterranean on their backs because the smaller birds could not fly that distance (p. 81). Today, we know that wagtails migrating from Europe to Africa gain weight before the trip, storing enough excess to travel across both the Mediterranean and the Sahara. Migration routes typically cross the Mediterranean at its narrowest points; wagtails arriving in Egypt may follow a land route around the eastern end of the sea.
Birds Spend the Winter in Caves and Trees
Some bats hibernate in caves and mines, so why not birds? Groups such as swallows and swifts were widely believed to hibernate in caves and hollow trees-a logical assumption for birds that nest and roost in these locations in summer. In reality, some swallows and swifts migrate more than 10,000 kilometres (6,000 miles), travelling in flocks during the day and feeding on flying insects as they go.
Birds Hibernate in Mud
Some birds were thought to tuck themselves away underground for winter, in burrows, or perhaps in mud, like some amphibians do. Corn Crakes were once thought to conceal themselves in this way, and Hogg recounts an instance of one being found dormant inside a mud wall (p. 435). These threatened Eurasian birds breed as far north as Norway and migrate to a relatively small winter range in eastern sub-Saharan Africa. Their migration routes are still not well defined.
The idea that birds hibernate is not entirely wrong. The Hopi Indians of southwestern North America spoke of "the sleeping one," the Common Poorwill, which becomes torpid and immobile at low temperatures and can remain in this condition for months until temperatures rise again (Perrins, 339).
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Sources:
Atlas of Bird Migration. Elphick, Jonathan ed. Buffalo: Firefly Books, 2007.
Birds in Legend Fable and Folklore. Ingersoll, Ernest. New York: Longmans, Green and Co.; 1923
Firefly Encyclopedia of Birds. Perrins, Christopher ed. Buffalo: Firefly Books, 2003
The Parlour Menagerie. Hogg, John. London: John Hogg & Co., 1878
Rosemary Drisdelle - Rosemary Drisdelle has been published many times as a nonfiction writer and several times as a poet. Her first book, Parasites: Tales of ...
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