Naturally Kiawah Magazine Volume 41 | Page 52

Marvelous Migrating Monarchs By Sue Corcoran H  ow to track a butterfly? Even as a child Fred Urquhart puzzled over this. They are too small to band and too fast to follow. Young Fred, like other curious observers, could only guess where butterflies went when he didn’t see them. Then in the 1930s Fred, who had become a biology professor at the University of Toronto, began to experiment with tagging monarch butterflies (Danaus plexippus). Hoping to learn where these beautiful insects go when they leave Canada toward the end of summer, he found tiny tags applied to the wings did not interfere with their flight. Forty years and thousands of tags later one bearing a small white disc was reported high in the mountains of a remote area of Mexico hibernating amidst millions of monarchs. This stunning discovery was the cover story in the August 1976 issue of National Geographic magazine The monarch, king of butterflies, is aptly named because of its size. With a wingspan approaching four inches it is the largest of North American butterflies and the only one to take part in a yearly migration that can total 3,000 miles. They do this flying approximately 100 miles a day at sustained speeds estimated at around 18 miles an hour, their wings beating five to 10 times each second. Scientists have observed precipitous declines in monarch populations since the 1990s. The National Wildlife Federation estimates the drop at an alarming 90 percent. Others put it even higher. They attribute this to habitat loss and herbicide use, both of which affect the availability of native milkweed (genus Asclepias). Monarch larvae feed only on milkweed, and they eat large quantities of it. The tiny caterpillar will increase its size over 2,000 times before entering the pupa state. Milkweed fuels this growth while its toxic properties provide protection from predators. No milkweed, no monarchs. We have known for many years that west coast monarchs winter in Southern California, and there has been general agreement that all monarchs east of the Rocky Mountains winter in Mexico or South America. Recently scientists noticed a sub-group in the Northeast that may not winter in Mexico. The hypothesis is that they may, like many of us, hunker down along the coast from South Carolina to Florida or perhaps venture on to the Caribbean or possibly Cuba. 50 Photo by Sue Corcoran