Four Wings and a Prayer: Caught in the Mystery of the Monarch Butterfly by Sue Halpern
Judging by the numbers of people who go to the various sites where Monarch butterflies gather for the winter in the mountains of Mexico there's great interest in this well-known migratory phenomenon. My own visit to their winter sites last February wasn't too successful. I have a pacemaker installed in my body and the altitude didn't agree with its functioning. To my regret, I had to remain in the base camp with my fast heartbeats while the other visitors went further up the mountain. However, last winter was cold and all they found were dead butterflies.
Monarchs are genuinely fascinating creatures and here's a book that really does justice to their story. The travel accomplished by Monarchs is simply mind-boggling. They fly forty miles a day on average but sometimes - depending on winds and weather - they can manage up to 200 miles between dawn and dusk. Those born to the East of the Rockies usually go to Mexico. Those born to the West mostly go to California. All flying is done in daylight - never at night.
How the Monarchs - millions of them - know when it is time to leave their summer breeding grounds and head south thousands of miles away is still one of the great unsolved mysteries of animal biology. So, too, is how they end up in the same spot, ten thousand feet up in a Mexican mountain forest year after year. They aren't guided by memory because no one butterfly makes the round trip. Three or four generations separate those that spend one winter in Mexico from those that go there next winter.
Says author Sue Halpern: "A Monarch butterfly born in August where I live in the Adirondack Mountains of New York State, for instance, will probably fly all the way to Mexico, spend the winter there and leave in March. Then it will fly north, laying eggs on milkweed along the Gulf Coast in Texas and Florida before dying. The butterflies born of those eggs will continue northward, breeding and laying more eggs along the way. So will their offspring. By August another Monarch, four generations or so removed from the Monarch that left my land for Mexico the previous summer, will emerge from its chrysalis hidden among the raspberry canes and do the same thing."
If we still don't know the explanations to these mysteries it's not for want of trying. One of the pleasures of Ms. Halpern's book is reading about the many people, scientists, academics and lay people, who devote their lives to tracking and observing and theorizing about the phenomenon of the Monarchs. Some are working in university labs while others spend months camping out alone in the Mexican mountains.
All along the various flight paths of the millions of Monarchs there are hundreds or even thousands of observers - individuals and organized groups - all watching out for the creatures. If they can find tagged butterflies they are invited to make reports to such as places as Monarch Watch at the University of Kansas or the Monarch Migration Association of North America (MMANA) in Cape May Florida. Some sites even invite collect calls to report the information on a tag.
I still have some trouble, even after reading the book, imagining exactly what a tag looks like. It is evidently a tiny circular dot of paper, like the piece of paper that comes out of a three-hole punch, stuck to the underside of the butterfly's wing. It would appear it is not an impediment to the creature's flying ability. And I still don't know how they get the pertinent data written on it. I guess I'll have to see one someday.
In addition to tags, one researcher, Lincoln Brower, has developed a way to "fingerprint" Monarchs by using an assay test to analyze the cardenolide content of a butterfly's guts. Cardenolide, the mixture that makes milkweed toxic, is found in varying concentrations in different species of milkweed. Brower perfected a method that allows him to determine which kind of milkweed a butterfly has ingested and, since these milkweeds grow in distinct regions, thereby to identify where each butterfly comes from.
Be advised that Sue Halpern has done her research well and doesn't hesitate to plunge into the various scientific aspects of her subject. There were a few pages where I found the technicalities rather heavy going. However, it's difficult to imagine a more thorough volume on the subject than this book. Many of the people she encounters on her travels are also very entertaining to read about. My own personal favorite was David Gibo, a glider pilot in Ontario, Canada, who does his butterfly observation from the cockpit of a Grob103 glider. Naturally, he has his own theories about how thermal updrafts and rising columns of air assist the butterflies on their incredible migrations.
Ms. Halpern is particularly good on the dangers that Monarchs face on their thousands of miles of travel.
"What is danger?" she asks. Weather, it would seem, is one of the greatest hazards in a butterfly's life during its migration. "Too cold and the Monarch can't fly, might freeze. Too hot and it gets overheated, can't fly. Too hot and there might not be enough water. Too much wind, grounded. Wind from the southeast, stalled. Wind from the west, blown seaward. Hurricanes. Tornados. Snow." All present dangers, and not just to Monarchs, but to their habitats as well.
And, of course, these admirable little creatures are not without predators. Wasps, fire ants, earwigs, aphids, rodents, birds and people are all dangerous. Cows like to eat Monarchs and Mexican farmers are known to bring cattle up to the wintering grounds and smoke the butterflies to earth, where the cows eat them by the thousand. Mice also like Monarchs. Then there are those herbicides and pesticides.
Believe me, it's not easy being a Monarch butterfly.
In my humble O: Sue Halpern has written a valuable and entertaining volume. As well as being an authoritative and first rate account of a fascinating subject, it's a damn good travel book and personal memoir.
Four Wings and a Prayer.
Caught in the Mystery of the Monarch Butterfly
By Sue Halpern
Vintage Paperback, 2002
Available from Amazon Books: Paperback