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Theory of transmutation vs. migration mythbusting

Posted: July 15, 2011 - 8:00am  |  Updated: July 15, 2011 - 4:35pm

Bird migration, the periodic movement of birds from one geographic location to another, has stimulated the imagination of mankind for thousands of years. Within certain passages of the Bible there appear to be references to observations of seasonal movement: Jeremiah 8:7 “Even the stork in the sky knows her seasons; and the dove, and the swift and the thrush observe the time of their coming”; and Job 39:26: “Does the hawk fly by your wisdom, and stretch her wings toward the south?”

Aristotle (384 BC-322 BC), the ancient Greek naturalist and philosopher, was reportedly the first to teach students on the topic. In his writings, he noted that certain species of birds would relocate from one region to another to seek warmer climates. He was also the first to observe that these birds would fatten themselves before their relocation. However, with all the correct information he accumulated, he is credited with beginning some of the more difficult myths to dispel.

The theory of transmutation, the seasonal change of one species into another, was developed by Aristotle. Redstarts in Greece migrate south in the winter, while robins migrate to Greece from northern regions. Before migration, redstarts begin to molt and lose their breeding plumage which convinced Aristotle that the redstarts changed into robins for the winter, and back into redstarts in the summer.

Another theory of Aristotle’s was bird hibernation. It is believed Aristotle, while studying swallows, observed late fall clutches of newly hatched swifts emerging from holes in trees and believed them to be the smaller-bodied swallows awakening from a featherless state of torpor (hibernation).

Aristotle’s myths spawned others such as “birds hibernate in caves like bats,” and a Barnacle Goose is so named because it turned into a barnacle for the summer.

It was not until the 1600s that French ornithologist Pierre Belan dispelled the hibernation myth by keeping an aviary of birds, purportedly of the hibernating variety, and although he provided all the necessities for hibernation, none ever did.

And, interesting to note, although the particular birds Aristotle observed are not hibernators, a 1946 ornithologist discovered that the Nuttals Poorwill, a species found in the Colorado Desert of California, does, in fact, hibernate.

Other myths born from observed migration strategies include “birds fly to the moon for the winter” — which is believed to have come about by the heights birds attain during migration. For example, Bar-headed Geese attain incredible heights of up to 29,500 feet while crossing the Himalayas.

There are still southern European cultures and some Native American tribes who believe that smaller birds “hitch” rides on the backs of larger birds in order to travel long distances. It appears these ideas came about not only because it seems impossible that a tiny bird such as a hummingbird can traverse either large land masses or oceans, but also from observing some bird behavior such as the harassment of larger birds by smaller birds.

All in all, the myths are born from the seed of desire to understand the phenomenon named migration. Thus began the concept of ornithology. In 1802, John James Audubon began a new age of scientific investigation of bird migration when he labeled birds with metal leg bands. Today, we continue the activity of bird banding which, combined with the new technologies of radar or satellite tracking, has yielded large databases of information. The North American Bird Banding Program is jointly administered by the United States Department of the Interior and the Canadian Wildlife Service. Their banding offices have similar functions and policies and use the same bands, reporting forms and data formats. Joint coordination of the program dates back to 1923.

To learn more about banding and the myth busting information produced as a result, visit http://www.pwrc.usgs.gov/bbl/.

Janet Schmidt is the Supervisory Park Ranger for Kenai National Wildlife Refuge. Previous Refuge Notebook articles can be viewed on the refuge website. You can check on new bird arrivals or report your bird sighting on the Kenai National Wildlife Refuge Birding Hotline at 907-262-2300.

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