Field Notes from Mexico from Dr. Bill Calvert

March 15, 2006

Listen to Dr. Calvert 

Gone were the swirling rivers of butterflies that descended and climbed the mountains with us each day that we had previous visited Pelon and Rosario.

Gone were the lower colonies at each of these locations. These colonies had presumably formed again higher up the slopes in the direction of their breeding grounds to the north. Only a few scattered flying butterflies remained in the former locations to attest to the masses that had occupied those positions only a week earlier.

And gone was the entire Chincua colony, said to have emptied completely last Friday and Saturday. The monarchs have started home en masse.

Wednesday afternoon, (3/15/06) an intrepid research team from St. Hubert’s Middle School in Chanhassen, Minnesota, began to scan the forest floor on the high altitude slopes of Cerro Pelon for mating butterflies. They were participants in a research project being conducted by Dr. Lincoln Brower to determine the amount of nutrients transferred from the male to female during the mating process. The results are not yet analyzed, but it’s believed that the amounts of lipids transferred may be significant.

Now we have some reports of students who have participated in the research program down here:

"Imagine trucking through foreign trees and flowers that are incapable of growing in your homeland. Next imagine these plants suddenly becoming alive fluttering with innumerable butterfly wings. Listening to the of millions fluttering of wings reminded us of traffic from distant freeways. As middle school students from St Hubert’s School in Chanhassen, Minnesota, we witnessed this reality in the monarch overwintering sites as we hiked through El Rosario and rode on horseback through El Pelon. Together these colonies hold approximately 10-15 million monarchs. In these breathtaking sanctuaries we were exposed to many different behaviors, for example, mating and cascading.

"After months of reproductive diapause, mating finally occurred because their reproductive organs matured. As the male takes charge he grabs and pins the struggling female to the ground in an attempt to transfer his genes to the next generation after a long flight. If the male is successful the female will begin the next generation of monarchs.

"As these days warmed to approximately 85 F the monarchs begin to break away from their clusters. Several times we saw them exploding from the boughs of the oyamel fir trees in a cascading behavior. The sky was thick with monarchs fluttering in all directions. We have been so fortunate to witness this spectacle and it has inspired us to learn more abut the mysteries the monarchs still hold."

The Monarch Research Team
Grades 7 and 8
Chanhassen, Minnesota