Migrations to the Moon: When Common Sense Flies South

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Three to four hundred years ago many people actually thought birds were capable of flying to the moon or hibernating on the seafloor. Of course, some folks at that time also believed barnacles could grow into a particular species of goose. Yes, a lot of strange ideas existed before the advances of modern science. Popular but erroneous beliefs included notions that smaller birds caught rides on the bigger birds, and that cranes, in their annual travels, preyed on Pygmies.

Under the Sea or Beyond the Sky?

Obviously, the understanding of birds’ migratory habits was rudimentary at best. Certain birds, such as the cuckoo and swallow, would appear around spring and disappear during the winter. People noticed this cycle, but as to how and why the birds vanished and came back was not so clear. One idea was that some birds, like several mammals, simply slept away the winter. Olaus Magnus, Swedish historian and archbishop, in his 1555 work Historia de Gentibus Septentrionalibus, appeared to think this about swallows, for he writes that fishermen had been known to pull these hibernating birds up from the sea with nets (1, 2, 3).

Magnus’s report on swallows, of course, seems today nearly as incredulous as the 1703 pamphlet “An Essay toward the Probable Solution of this Question: Whence come the Stork and the Turtledove, the Crane, and the Swallow, when they Know and Observe the Appointed Time of their Coming”. This document actually claimed that birds migrate to the moon (4, 5). And, no, this is not a joke!

Imagining our winged friends on a lunar flight or residing under the sea is quite farfetched today. The strained logic behind such mistaken notions, however, is still understandable. After all, the last time some people may have seen certain birds was probably as they were flying over a large expanse of water or beyond the horizon at evening time. Folklore, with its strong associative leanings, could have simply connected the birds’ destination with the last place they were observed.

What was Aristotle Thinking?                           

Even the ancient Greeks, despite their many contributions to science and philosophy, were susceptible to incredible stories. One of the most fascinating accounts of bird migration comes from Homer’s Iliad (Book 3: 1-6), which describes cranes attacking Pygmies (6). Moreover, Aristotle—yes, the great classical philosopher—notes the Pygmies’ African location in his History of Animals (Book 8: Chapter 14). Actually, in his landmark work, the first extensive biology book of antiquity, Aristotle provides the most original detail of any classical writer on birds. Unfortunately, he promotes quite his share of misconceptions, too.

To account for the annual appearance and vanishing of different birds, Aristotle cites migration, but he does so along with a couple other alternate means. For instance, some feathered creatures, he claims, can morph from one species into another, such as redstarts transmuting into European robins and back again (Book 9: Chapter 26). Also, according to Aristotle, several birds, including turtledoves, thrushes, starlings, and some swallows, hide away slumbering for months in seclusion, basically hibernating until warmer weather arrives (Book 8: Chapter 18). Interestingly enough, notwithstanding such off-the-wall notions, Aristotle wasn’t completely wrong about hibernation. Scientists have recently learned that a few birds, such as the common poorwill and swallow, can rest in torpor during brief cool periods (7). Of course, though, they don’t sleep under water, as Magnus asserted.

Despite numerous missteps, our ancestors were clearly not clueless. Thousands of years ago, many people realized that at certain times bird populations traveled from one region to another. References to such cycles can be found in other ancient texts, such as the Bible (e.g., Job 39: 26-30, Jeremiah 8:7), Herodotus’s The Histories (e.g., Book 2: Chapter 22), and Aristophanes’ plays The Birds and The Knights. So, at the very least, ancient people seemed aware when seasonally certain birds arrived and departed.

Of course, by today’s standards our knowledge of bird migration has matured considerably. For more on the intriguing history of how this understanding has developed, including a particular white stork’s important role in the process, please check out this blog post from a scientist at the Royal Society for the Protection of Birds (RSPB).

Sources:

  1. Armstrong, J., Lienhard. R. “No. 2228: Ancient Explanation of Bird Migration”, Engines of Our Ingenuity. University of Houston: http://www.uh.edu/engines/epi2228.htm.
  2. “Migration of Birds: Early Ideas About Migration”, Northern Prairie Wildlife Research Center. U.S. Geological Survey: http://www.npwrc.usgs.gov/resource/birds/migratio/ideas.htm.
  3. Bond, A. “How did we learn that birds migrate (and not to the moon)? A stab in the dark,” 11/3/2013. The Lab and Field: http://labandfield.wordpress.com/2013/11/03/bird_migration/.
  4. “Migration of Birds: Early Ideas About Migration.”
  5. Bond, A.
  6. Armstrong, J., Lienhard. R.
  7. “Migration of Birds: Early Ideas About Migration.”
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