Migration

September 2014

Factoid September 25, 2014

Moth-Eaten Migration Myths

Thanks to modern technology and data sharing, scientists understand quite a bit about avian migration. Naturalists prior to the 17th century, however, didn’t have access to the GPS trackers, citizen science projects, or even bird bands that many ornithologists rely on today. Take a look at some of the wackiest historical theories about bird migration below.

Hibernating in a Hole


Photos © Dave Biddle

For over 2,000 years, it was believed that while some birds migrated, others hibernated through winter in the same locations in which they summered. How the birds managed to survive the cold, it was reasoned, was by finding a snug crevice or a hole in a tree and hibernating, just as some mammals do. Aristotle was the first to claim that Kites, Doves, Storks, and Larks all spent the winter in hibernation. The popular idea likely sprung from the discovery of dead birds in holes along river banks, where the birds had unsuccessfully sought shelter from inclement weather. Today, only the Common Poorwill is known to hibernate through winter, though many songbirds will go into a temporary state of torpor to survive an especially cold night.

Sleeping Beneath the Waves


Photos © Mike Bush

Similar to the theory of hibernation, it was a widespread belief beginning in the 1500s that swallows and swifts survived the winter by burrowing deep into the mud at the bottom of lakes. Fishermen were said to net birds along with the fish, and many trusted scientists claimed to see with their own eyes groups of swallows submerge themselves by fusing together and climbing down reed stalks. This theory was so persistent that in 1878, respected ornithologist Dr. Elliott Coues collected the titles of 182 papers dealing with the topic. The origin of such a belief likely stems from the fact that migrating swallows prefer to roost on standing reed beds, and often leave before daybreak.

Going My Way?


Photos © David Stephens

So pervasive was the disbelief that small birds could manage flying such long distances, this next myth seems to have arisen concurrently all around the world. Some native tribes in North America believed hummingbirds migrated on the backs of geese, while in European countries, songbirds were believed to wait on the shores of the Mediterranean until the storks arrived and the small birds could be ferried across. The notion persists even today in some regions of Eastern Europe. This image of small birds mooching rides from large birds likely came about due to the ease of viewing the diurnal migration of large birds, as opposed to the largely unseen nocturnal migration of small birds.

Now You See Me…


Photos © hawk person

Aristotle can be credited for another lasting theory on where birds went in winter – he believed often one species morphed into another. The simultaneous emigration of one species with the sudden appearance of others caused the famous philosopher, as well as many others throughout the years, to conflate the two. Redstarts molted and became robins. Even into the early twentieth century, much of the rural population of England believed that cuckoos were transformed into hawks at the start of winter, likely due to the similarities in their plumages. This transition was not simply limited to birds – the crustaceans we know as barnacles have their name because they were believed to be the winter form of Barnacle Geese!

Moonward Bound


Photos © Shawn Harquail

Perhaps the most extraordinary theory, in 1703 it was thought by a small subset of the population that birds migrated to the moon for winter. A fifty-page pamphlet, published anonymously by ‘A Person of Great Learning and Piety,’ claims the journey to the moon takes sixty days, during which birds do not have to eat, and mostly sleep on the wing. He proposes that small rocky astronomical bodies along the way may be used as rest stops, and that the birds do not fly towards the moon so much as fly up blindly and eventually reach the moon by coincidence. The pamphlet concludes that if the moon isn’t a viable migration destination after all, then the birds must be going somewhere else. It is believed this theory arose out of observations of the height some birds attain while migrating.

Add to our understanding of migration!

Citizen Science projects like Project FeederWatch and eBird help collect important data for researchers to analyze and add to our knowledge of migration routes and destinations!

Bibliography
Butterfield, R. (1909, February 1). An Early-Work on Bird Migration. Zoologist, 71-73.
Clark, W. (1927). Studies in Bird Migration (pp. 1-10). London.
Dixon, C. (1892). The Migration of Birds (pp. 1-10). London.
Dixon, C. (1900). The Story of Birds (pp. 150-159). London.

This Month’s Articles

Moth-Eaten Migration Myths

Factoid

The Green Wave of Migration

Research Recap September 17, 2014

The One Thing You Can Do To Help Migrants

Take Action September 10, 2014

Does It Migrate? Quiz

Interactive September 3, 2014

One Comment

  1. Many theories of migration of the birds present another myth. They have no theoretical justification. However, these theories allow building the completely logical conclusions.

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