To the Moon and Back: Early Explanations for Bird Migration

Today, the concept of bird migration is roundly accepted as a scientific fait accompli. Ornithologists have proven that annually many avian species travel short, medium and long distances from their non-breeding grounds to locations most favorable for reproduction. That's not to say that many mysteries don't still exist. They certainly do. For instance, the Bird Conservatory of the Rockies was instrumental in unlocking where the wraith-like Black Swift winters before returning to Colorado each spring. The answer is western Brazil's Amazonian rainforest. That's a yearly round-trip of more than 8,000 miles.

However, the accurate understanding of bird migration is a fairly new concept to Western science. For thousands of years, some of history's most noted thinkers puzzled over the cause of various species' departure and seemingly miraculous return. Here are just some of their hypotheses.

We may laud the 8th Century BCE Greek poet Homer for his timeless tales of the Iliad and the Odyssey. But his thoughts on bird migration certainly don't stand up. Homer espoused that the Common Crane, which breeds in Northern Europe and Asia before migrating to the Middle East and Western Africa, annually fought pygmies on their voyage in a non-ending war for survival. 

More than 700 years later, this fantasy is echoed by Roman naturalist and scientist Pliny the Elder. He postulates that the pygmies, armed with bows and arrows, keep up their combative strength by riding goats and rams to raid the eggs of Common Cranes for food.

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No less a thinker than Greek 4th Century BCE philosopher Aristotle posited two ideas about bird migration based upon his observations. First, he believed Swallows hibernated at the bottom of lakes and swamps. Second, he thought species that departed in the fall transformed themselves into those that arrived in the winter.

Thinkers still embraced Aristotle's migratory explanations 1,900 years later. A 1555 woodcut used to illustrate a treatise by Swedish Archbishop Olaus Magnus depicts winter fisherman hauling in a net laden with sleeping Swallows. Magnus' advice: attempting to warm them causes death, so leave them be. 

About 130 years later, Charles Morton, one of the United States' first textbook authors, took a stab at explaining migration. His idea: that birds of all sorts wintered on the moon before returning to earth. The idea excited Morton because he was certain that if birds could make the lunar trek, humans could, too. (In that, he wasn't wrong.) Morton's text was a staple at both Harvard and Yale for the next 70 years.

It wasn't until 1822, or three years before the first established railroad, that the Western world received definitive proof of long-distance migration. It came to Mecklenburg, Germany in the form of a live White Stork with an African tribal arrow piercing its neck. The German's dubbed the bird, "Pfeilstorch" or "arrow Stork." It provided undisputable proof that birds migrated farther than the human mind at the time could comprehend. 

Which is interesting, because each past century was certain of their scientific knowledge. So it makes one wonder, what marvels of migration still exist beyond the horizon, waiting for future generations to translate? 

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