Whodunit: cold air or angry loggers?

Annually, millions of monarch butterflies migrate from the United States and Canada to Mexican mountains, striking wonderment in visitors and scientists alike. But an event this year has brought the political dimension of the monarchs into stark relief: the deaths of millions of butterflies at the San Andres reserve.

It's unclear whether the cause was sabotage or cold temperatures. But either way, the doom of this colony of lace-like orange and black insects appears to have stemmed from human intervention, raising questions about its future.

Earlier this month police visiting the San Andres reserve in Michoacan state were shocked to find the dead colony, which they'd encountered as healthy and bountiful only a few days earlier. The police reported a heavy chemical smell mixed with gasoline fumes in the area, and they said the dead butterflies - in some places nearly a foot deep - exhibited an unusual iridescent glaze.

Local police and Mexican environmentalists claim that clandestine loggers sprayed the monarchs, who huddle for warmth on the commercially valuable oyamel fir trees.

But the Mexican government, sensitive to domestic and foreign accusations that Mexico does not adequately protect the monarchs, has a different theory. Mexico's environmental protection agency, Profepa, says the butterflies died from the cold, and that a study of 300 specimens found no traces of chemicals.

But even that claim has a dark side. If the monarchs died of exposure, it was probably because illegal logging in the reserve has thinned out the normally dense oyamel forest. Without the thickly knitted fir trees, the monarchs can be exposed to cold snaps and chill winds.

"With these disputed theories over the cause, the only fact we have is that more than 5 million butterflies are dead," says Homero Aridjis, a prominent Mexico City environmentalist and monarch champion. "But whether it was cold or spraying that did this, the ultimate responsibility lies with the uncontrolled logging that is ruining these sanctuaries."

Mexico first established reserves in 1986 to host the monarchs, which arrive every November and stay several months before beginning the several-thousand-mile-long journey back in late March. Last year, then-President Ernesto Zedillo tripled the reserves' size to 130,000 acres after a government study found that nearly half of the monarchs' fir forests had been damaged or destroyed.

As part of the expansion, the government also announced several programs to pay loggers while they learn another trade or train for a different job.

But many loggers still condemned the sanctuary expansion as an attack on local communities. Some vowed privately to continue making their living from tree cutting in the newly off-limits areas. In this overheated context, the butterflies became the loggers' enemies - a possible motive, some say, for attempts to get rid of the popular monarchs.

Yet, although Profepa discounts the sabotage theory, it does not deny that illegal logging has reached devastating levels.

"The level of surveillance of the monarch reserves has been considerably stepped up under this administration because of the damage we encountered," says Profepa spokesman Manuel Gallardo, referring to President Vicente Fox, who took office in December.

This is hardly reassuring, Mr. Aridjis says, claiming that many state and local officials are in the pockets of Michoacan's powerful logging interests.

Noting that Mr. Fox has declared conserving Mexico's dwindling forests a matter of "national security," Gallardo says the new government cannot be accused of neglecting forests.

But according to the Alliance of Communal Land Communities of the Monarch Butterfly Reserves - an organization of communities promoting monarch-friendly development - two board feet of wood is illegally logged from the reserves for every foot of legally cut wood.

Aridjis recalls another heavy kill of monarchs in 1995, which environmentalists blamed on illegal logging that left the butterflies to freeze. "The government went to great lengths to try to show that the butterflies were not dead but only temporarily inactive," he says. "They had specialists on TV blowing their warm breath on live butterflies to show that [the environmentalists] were wrong, that supposedly dead monarchs could be revived."

Adds Aridjis, "Every time there's been suspicious butterfly mortality like this the government tries to discredit us, but they never go after the loggers."

(c) Copyright 2001. The Christian Science Monitor