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Mexico blames north for fewer monarch butterflies

The population of Monarch butterflies in Mexico has suffered a drastic decline, but the government is now blaming the United States and Canada, not deforestation in Mexico itself.
A Monarch butterfly sits in the Mexican forest where millions migrate to each year from North America.
A Monarch butterfly sits in the Mexican forest where millions migrate to each year from North America.Marco Ugarte / AP
/ Source: The Associated Press

The population of Monarch butterflies has suffered a drastic decline, but Mexico — where deforestation has long devastated Monarch wintering grounds — is now blaming the United States and Canada.

Mexico’s Environment Department said on Wednesday that 75 percent fewer Monarch butterflies have appeared in 2004 compared to previous years.

It blamed cold weather and intensive farming — including genetically modified crops — in areas of the United States and Canada where the butterflies spend the summer and reproduce.

In past years, Mexico acknowledged the butterflies were affected by illegal logging of the central Mexico fir forests that make up the winter nesting grounds.

Skepticism on ground
Activists and researchers suggested Mexico may be trying to offload some of the blame, after its own highly-publicized efforts to stop illegal logging ran up against often violent resistance from logging gangs.

“This is an incomplete and tendentious report, that seeks to put all the blame on other countries which do share responsibility,” said Homero Aridjis, whose Group of 100 environmental organization has long opposed illegal logging.

The Mexican government said the decline was due to a number of factors, including an unusually cold summer in the United States and a high mortality rate for the butterflies in Mexico in 2003 due to cold, wet conditions.

“It is clear that the migratory phenomenon of the Monarch Butterfly ... is not at risk,” the Environment Department said. “This is a species with a great capacity for recovering from die-offs.”

However, the announcement focused almost exclusively on events in the United States and Canada, including “industrial agriculture that displaced breeding and feeding grounds,” “the use of herbicides and loss of habitat,” and the planting of genetically modified crops not used in Mexico.

Forests 'in full recovery'
The government claimed Mexican forests “are healthy or in full recovery,” and that logging had been completely eradicated in the butterfly reserves, statements disputed by activists like Aridjis, who say illegal logging is a huge problem.

“The main problem is the illegal loggers,” Aridjis said. “If nothing is done, looking at it pessimistically, we’re going to see fewer and fewer butterflies.”

In some widely publicized laboratory experiments, Monarch butterfly caterpillars did die after eating milkweed coated with genetically modified corn pollen. In its own studies, the U.S. Environmental Protection Agency said there probably is little risk to butterflies.

While acknowledging that U.S. and Canada factors played a role in the butterflies’ problems, one researcher who spoke on condition of anonymity said Mexico was trying to put a spin on the research results.

The announcement was based on a report of total nesting ground areas prepared by Mexican government agencies, the World Wildlife Fund, and Mexican and U.S. researchers.

Researchers measured the area covered by butterflies, a fairly accurate indicator since they tend to literally blanket forest areas in dense orange-and-black clumps.

In Mexico from October-March
The government called the conclusions preliminary, based on reports from 12 of the 22 nesting grounds, and said they would have to be confirmed with further study.

The annual arrival of butterflies from across North America to winter in Mexico — where they stay from October to late March — is an aesthetic and scientific wonder.

The butterflies have proved remarkably resistant to both natural and manmade threats. In 2001, driving rain and bitter cold killed millions, leading scientists to speculate that migrating populations would be seriously depleted in 2002. To their surprise, anywhere from 200 million to more than 500 million monarchs returned that year — twice as many as some predicted.