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My thanks to Tom Wilmoth of the Bedford Bulletin for making me aware of this opportunity to hear a man whose work I have long admired. A few weeks ago (Feb. 27th), because of Tom's "heads up", I was privileged to hear Dr. Lincoln Brower's lecture on the amazing migratory phenomenon of the monarch butterfly. The lecture was given at Sweetbriar College, where he is research professor of biology.
Prof. Brower's educational and career credentials are impressive,to say the least. He earned his B.A. in biology at Princeton University in 1953, then went on to receive his PhD in zoology at Yale University four years later. Subsequent years were spent at Oxford University, Amherst College, the University of Florida, and finally here at Sweetbriar College in Virginia. He states that he has "been a student and admirer of the monarch for more than fifty years".
His present area of research, and the topic of his lecture, is the migration, overwintering, and conservation considerations, of the monarch butterfly. He is currently recognized as a world leader in this field of research. Prof. Brower bigan by emphasizing that it is not the existence of the species which is currently endangered, but the fantastic journey made each year by part of the species. Numerous articles and TV specials have aroused public interest in this uniquely North American spectacle of millions of one species of butterfly flying from wintering sites in the mountains of central Mexico acoss the United States to Canada and then returning to the same winter spots the following fall. Because the entire journey takes a full year, three or four generations of butterflies are required to complete it. This means that while the butterflies have been inactive for the five months spent in their winter site, when spring arrives they must now begin their long flight north. They breed and lay eggs as they go, so that there will be a new generation to follow them. This new generation will continue on the route their parents have taken, laying more eggs for the next generation. finally to turn about and start the trip back. This is a cycle that has been repeating itself for an unknown number of centuries.
Dr. Brower spoke, and presented eye catching photos, of, Mexican wintering sites where millions of monarchs cling, unmoving, to fir trees, completely covering the trees, from November through most of March. So far as has been discovered through aerial surveys, there are only twelve such sites in a relatively narrow band of mountains, where all of the monarchs we see here in the eastern U.S. go to spend the winter. If these sites are lost, the entire population of migrating monarchs will be lost. Sadly, the butterflies which have flown so far are still in danger in these oyamel fir forests high in the mountains of Mexico. In their dormant state they are easy prey for birds that can tolerate the toxic chemicals these butterflies have accumulated in their bodies from their caterpillar diet of milkweed. Weather, also, may destroy many. His research has shown that they they are most vulnerable to cold accompanied by wet. Under this combination many will freeze. In one tragic winter most of those wintering in several sites died, falling to the ground below and creating a coating eighteen inches deep of dead and dying butterflies.
Sadly, even though, in 2008, the area was recognized as a UNESCO "World Heritage Site', trees in and near the monarch refuge continue to be cut and used as lumber illegally. In addition to this loss of winter habitat, a variety of challenges to the migratory population exist in the U.S., where the breeding population depends on milkweeds for the caterpillars to eat and nectar producing flowers for the adults to fatten on for the long journey. Numerous groups promote the planting of milkweed in "butterfly gardens". When I asked Dr. Brower whether this seemingly small effort had any hope of saving the dwindling phenomenon of the monarch migration, he pointed out the political nature of many of the threats to it, and added "keep up the noise level".