The Waning Reign of Monarchs
Wednesday, February 23, 2005
CERRO PELON, Mexico -- High on a remote mountaintop, Alfredo Cruz Colin gazed at a panorama of giant pines and firs where millions of orange and black monarch butterflies spend the winter after flying as far as 2,000 miles from Canada and the United States. He saw two things: one of North America's most spectacular natural wonders and trees that could be sawed down and sold for $300 each.
"We can contemplate the butterflies," said Cruz, a lawyer. "Or we can send our children to school and feed our families" with the cash from the cut trees. "It's a tough choice."
The winter migration of monarch butterflies to Mexico, a stunning sight that draws vast numbers of tourists to mountain forests 100 miles west of Mexico City, has been devastated this year. One of the chief causes is logging that destroys butterfly sanctuaries, according to Mexican and U.S. environmentalists.
The butterfly population this winter is the lowest since researchers began detailed surveys 12 years ago and perhaps the smallest since the 1970s, when international scientists first discovered the colonies in central Mexico, according to Lincoln P. Brower, a biology professor at Sweet Briar College in central Virginia and an authority on monarch butterflies. He estimated that the population was at least 75 percent smaller than last year's.
In the last two years the butterflies carpeted an area spanning more than 20 acres, but this winter they cover a little more than five acres, said Ernesto Enkerlin, chief of protected areas for the Environmental Ministry. "We are not happy about having fewer monarch butterflies," he said.
The reason for the dramatic drop appears to be a combination of particularly cold, stormy weather in North America in recent years, herbicide use in the United States and Canada that is killing milkweed plants where butterflies lay their eggs, and persistent illegal logging in Mexico, according to a report issued last week by a panel of monarch researchers chaired by Brower.
Experts and officials agree that all three factors have contributed to the decline in the butterfly population, but there are differing views on whether the greater blame lies with nature or man. Brower said that without further study, it was impossible to determine what portion of the damage was caused by each factor.
But it is clear that the northeast face of this mountain has "been stripped of forest and burned," destroying long-established butterfly sanctuaries and leaving only one small butterfly area this year, said Brower, who has visited the site almost every year since the mid-1970s.
Conservationists are also concerned about threats from herbicides, which they say are killing thousands of acres of wild milkweed plants in the midwestern United States and Canada. While genetically engineered crops such as soybeans and corn are resistant to the chemicals, the weedkillers are causing massive destruction of butterfly eggs on milkweed leaves, they said.
"Why should we care?" said Brower. "For the same reasons we should care about the Mona Lisa or the beauty of Mozart's music."
On this chilly mountaintop, reachable by a long, steep horseback ride up to 10,000 feet above sea level, butterfly colonies hang like enormous orange-and-black beards of Spanish moss. As they stirred to life this past weekend, warmed by the afternoon sun, and took flight by the thousands, Elidio Renya Corona, a park ranger, lamented that the size of the colony had shrunk this year and that loggers were "wiping out" the butterflies' winter home.
Officials at U.S. and international conservation organizations, which have donated millions of dollars to protect the migrating butterfly, said they were also alarmed at the shrinking population. They noted that in Chincoteague, Va., and Cape May, N.J., two important stops along the monarch route to Mexico, researchers also reported a record low number of migrating butterflies as they passed through last fall.