Monarch butterflies emerging in the fall are a different sort than ones coming out during the summer. Instead of mating and laying eggs, fall monarchs congregate on trees, then fly south to Mexico, where they hang on the oyamel trees in the transvolcanic mountains near Mexico City.

          Scientists interested in monarchs once did not know where monarchs went when they disappeared in the fall. In the 1950s, a Canadian scientist and his wife, Fred and Nora Urquhart, devised a tagging system in order to track the monarchs and try to discover where they over-wintered. Dr. Urquhart prepared tiny paper tags printed with his name, address and a number, and publicized his need for volunteers to place the tags on migrating monarchs.

 People tagging butterflies from their hometowns kept a record of the tags they used, and sent the record sheet to Dr. Urquhart. As tagged butterflies were spotted and reported, Dr. Urquhart began to learn where they had traveled from and how far.

Finally, in 1975, as a result of the tagging project, the roosting places in the mountains of Mexico were discovered. (Story and pictures are in National Geographic listed below).

The tagging of monarchs continues, even though scientists know the over-wintering sites. They have more questions to be answered: the size of the migration; the routes taken by the migrants; what part of the country most monarchs come from and many other questions that can be answered through tagging.




http://www.monarchwatch.org/ Monarch Watch


Herberman, Ethan The Great Butterfly Hunt: The Mystery of the Migrating Monarch. Simon  and Schuster Inc., New York 1990


National Geographic “Discovered: The Monarch’s Mexican Haven” Fred A. Urquhart. August 1976


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