Monarch Butterfly Habitat
Air Date: Week of January 28, 2000
In a story originally broadcast as part National Geographic's Radio Expeditions, John Burnett takes us to Mexico to profile the people who are trying to protect the fragile habitat of the migratory Monarch butterflies.
CURWOOD: It's Living on Earth. I'm Steve Curwood. The monarch butterfly is one creature that may be at risk from genetically-modified organisms. Researchers have found in lab tests that pollen from corn designed to produce a moth-killing toxin also kills monarch caterpillars. An industry-funded study disputes that result. Even so, the EPA recently announced that seed companies must now ask farmers to plant a buffer zone of natural corn around genetically-altered crops to help assure butterfly habitat. Poison pollen or not, the monarch faces other real threats as well, as we hear in this National Geographic Radio Expedition from Mexico, where the butterfly spends the winter. NPR's John Burnett reports.
(Mariachi music and traffic up and under)
BURNETT: In the maddening heart of Mexico City, it's possible to imagine this metropolis as a super-mound, an insect colony out of control. With relief, our VW van lurches through the brown haze and over the lip of the Baya de Mexico. We're on a journey to see how another species manages to survive in countless multitudes. Rising in the distance are the volcanic mountains of Michoacan, the winter home of los monarcas. At the wheel is a tall, rumpled man in a ski sweater and corduroys who maintains a secret stash of Milky Ways and a lifelong infatuation with Danaus plexippus, the monarch butterfly. Dr. Lincoln Brower of Sweet Briar College in Virginia has trekked to these mountains nearly 50 times.
BURNETT: We turn off the pavement, climb a bumpy road, and unload in a butterfly reserve almost two miles high, called the Sierra Chinqua.
BROWER: We've gotten all our gear together, and we're up here in the Yanas de Villa Lobos, which is the staging area just below the ridge of mountains where the monarchs form their colonies. And it's about a mile walk from here to the butterflies.
BURNETT: All around us are Oyamel firs, where some 250 million monarchs will over-winter in a normal year. Stopping along the way to refuel on nectar, they fly from Canada and the United States east of the Rockies in a huge migrational funnel that ends in the Oyamel forest. No one is sure exactly why the monarchs pick these mountains. It may be because, as a rare east to west range, they're a natural barrier with the right vegetation and altitude.
BROWER: We head off this way to the left.
BURNETT: How the butterflies find their way here is another mystery. The fall arrivals are the great-great-grandchildren of the generation that departed eight months earlier in the spring.
BROWER: So they have no memory of how to get here. It has to be in their genes.
BURNETT: And then we see them, hanging in great gray clumps like Spanish moss drooping from fir boughs. They remind Brower of feather dusters. When the sun hits a colony and the insects warm up enough to fly, they look like pieces of black and orange stained glass, and sound faintly like the whispers of saints.
BROWER: So here we are now, approaching the center of this colony. And this colony here is about two and a half hectares of butterflies. So we're talking about 21 or 22 million butterflies that are just surrounding us here.
BURNETT: As many butterflies as the population of Mexico City, hanging here, quiescent, from November to March, until longer, warmer days jump-start their gonads. Then they surge into the air for a month of frenzied in-flight lepidoptrous lovemaking. Afterwards they ride the northward winds back across the Rio Grande, to lay eggs on milkweed plants from Brownsville to St. Augustine.
BROWER: It's very beautiful, and to think of an insect that weighs about as much as a penny flying all the way down here from Toronto, Canada, and then getting back, surviving the winter, and getting all the way back to the Gulf Coast, laying its eggs and setting the stage for the next generation.
BURNETT: Brower and other researchers are worried the monarch's forest habitat is threatened by compasinos who conservationists say cut the protected Oyamels with impunity and run their cattle in the forests. He's noted the colonies are half the size of last year's, which could be related to timber cutting as well as to recent forest fires and the drought. We're traveling with a friend of Brower’s, Mexican poet and environmentalist Omero Aregis. He was largely responsible for the Mexican government setting aside this and several other mountaintops as butterfly reserves. He sits on a fallen tree and looks up at a cluster of sleeping butterflies.
AREGIS: We were allocated to respect the masterpieces of human beings through history, Michelangelo, and the museums. But we don't respect the masterpieces of nature, and the monarch butterfly is a masterpiece of nature. And the phenomenon is fantastic, fantastic.
BURNETT: Brower is trying to understand why the Oyamel firs are so important to the butterflies, and in the process he wants to create more reasons to protect the forest. To that end we climb a narrow path lined with fragrant wild sage and pink thistles, to a stand of large trees.
BROWER: The reason we're here is because I want to measure the temperature of the trees, to see if they can act like a hot water bottle. We want to test this hypothesis, because when it gets very, very cold, the butterflies that are on the tree trunks show the highest survival rate.
BURNETT: He drills a hole in a trunk and inserts a thermal probe. It will register the tree's temperature for the next 40 days.
BROWER: Will you hold that? Okay. So, we need to get the diameter of the tree, but let me get this hole under control. Okay. (Grunts) We have to try to get this hole in as straight as possible. (Hammers)
BURNETT: The butterfly reserves have never been popular with the local people. The mountaintops used to belong to them. Now they try to make money from tourism, charging admission, hiring out as guides, renting horses, and selling souvenirs.
BURNETT: But if you ask people here at the stables on the edge of the reserve, they'll tell you they want to be compensated for the reserve land or allowed to take out more wood.
MAN: [Speaks in Spanish]
TRANSLATOR: The falling timber just rots, and our children don't even get to benefit from it. They won't let us cut anything, not even haul out the fallen wood. What we need is permission to restore the forest and plant new trees, so the forest is beautiful. It's newer, and so the butterfly would be happier here.
BURNETT: Researchers are skeptical the local compasinos are as conservation-minded as they sound.
BROWER: Basically, what we are seeing here in Mexico is the Achilles heel of the whole migratory phenomenon, because of the dependence on these forests. This is the entire seed crop of the monarchs that migrate back into the United States and Canada. So if we lose this, if the site deteriorates, and the butterflies can't make it through the winter here, then we're going to lose the whole migration. And I honestly believe, based on 22 years of research up here, that we're getting close to the no-turning point.
BURNETT: If the Aztecs were right, these monarchs will never leave because they cannot. The ancient Mexicans believed the butterflies to be the souls of dead warriors. An Aztec scribe wrote this.
BROWER (reading): Perpetually, time without end, they rejoice. They live in abundance, where they suck the different flowers. It's as if they look drunk with joy and happiness, not knowing, no longer remembering the affairs of the day, the affairs to the night. Eternal is their abundance, their joy.
BURNETT: Eternal, Lincoln Brower suggests, as long as the Oyamel forest is safe. I'm John Burnett for Radio Expeditions, in the Sierra Chinqua, Mexico.
CURWOOD: Our report on the monarch butterflies was produced by Jessica Goldstein and recorded by Leo Del Aguila for NPR's Morning Edition, and originally broadcast as part of the National Geographic Radio Expeditions series.
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