Do monarch butterflies need space on the North American summit agenda?

Canada, Mexico, and the US seem on the verge of losing a great, mysterious natural migration. The number of monarchs returning to Mexico plummeted this winter.

By , Staff writer

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    A Monarch butterfly sits on a tree trunk at the Sierra Chincua Sanctuary in the mountains of Mexico's Michoacan state, in 2011.
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No one knows over how many millennia monarch butterflies have made their epic migration from one end of North America to the other.

The mountainous winter home of the delicate orange and black creatures was only discovered in the oyamel forests of central Mexico in 1975. Twenty years later the feather-light insect was unofficially adopted as the symbol of the nascent North American Free Trade Agreement, since the monarch’s multi-generational trek, more than 2,500 miles long, takes the species to the three NAFTA countries.

But now Canada, Mexico, and the United States seem on the verge of losing one of the natural world’s great and mysterious migrations. The number of monarchs returning to Mexico, already in steady decline, plummeted this winter.

Recommended: How much do you know about Mexico? Take our quiz.

The unprecedented drop in wintering monarchs has prompted environmentalists and scientists from across the hemisphere to plead for last-ditch action from the three North American leaders – President Obama, Mexico’s President Enrique Peña Nieto, and Canada’s Stephen Harper – during a joint summit today in Toluca.

Toluca is only a few miles from one of the monarchs’ central Mexico sanctuaries, so advocates say it would be all the more fitting for the leaders to take a stand for the monarchs here.

“We think we are in a very critical moment, and that is why we have issued this call to [the three North American leaders] to take action,” says Omar Vidal, director general of the World Wildlife Fund’s Mexico office. “We feel this may be the last opportunity to save the monarch migration.”

This winter a survey of Mexico’s monarch sanctuary found butterflies covering just over one and a half acres of forest, a 44 percent decline from a year ago. More striking still is the comparison of this year’s forest coverage with the peak year, 1996, when the monarchs occupied nearly 45 acres. 

Armed with those statistics, directors of WWF’s three NAFTA-country offices last week sent a call to action to the three North American leaders. But the primary target of the WWF campaign and similar ones is Obama. Most monarch specialists agree that the most critical factors in the recent steep decline originate in the US.

The large-scale loss of milkweed, the monarch’s lifeblood, across the American Midwest and the ever-increasing use on US farms of herbicides, especially the weed killer Roundup, are two of the biggest factors in the decline.

“We’re not saying there is only one cause and one country responsible for this decline,” says Mr. Vidal. Climate change, the advent of more extreme weather, and deforestation are also factors. “But we know the monarch depends on milkweed, and it’s the disappearance of large areas of milkweed from the US corn belt in particular that is having an impact.”

'Great natural phenomenon'

This is a switch from the 1990s, when most of the blame for what was already considered the monarchs’ precarious existence was directed at Mexico. Little attention was paid to milkweed then, but significant pressure was applied to Mexican authorities to stop the rapid deforestation of the areas the monarchs inhabited.

And what became an international campaign seemed to work: Mexico established the Monarch Butterfly Biosphere Reserve in 2000, and while illegal logging didn’t stop immediately, deforestation in core butterfly areas declined sharply.

Even Carlos Slim, the Mexican billionaire and philanthropist often listed as the world’s richest individual, has joined the effort to preserve Mexico’s monarch sanctuaries.

Reversing the loss of milkweed – where monarchs lay their eggs, and the plant on which the monarch caterpillars feed – might seem at least as achievable as saving forest in a high-poverty region of Mexico. Just let the milkweed grow back, and stop using herbicides, some would say.

But the loss of milkweed is directly tied to the boom in US corn and soybean exports, and the growth in ethanol production in recent years. With international grain and soybean prices so high, any effort to leave acreage fallow to grow milkweed is likely to meet stiff resistance, some farm belt experts say.

Monarch specialists note that the urbanization of American and Canadian rural lands where milkweed once grew is also a factor. There is now a growing grassroots campaign across the US to plant milkweed in backyards and along highways.

Every little bit of milkweed can help, WWF’s Vidal says. But he adds that it will take not just a few backyard plants here and there, but a massive effort – and very soon – if the monarch migration is to be saved.

The monarch is not threatened with extinction, Vidal says. There are enough separate populations – including the second largest, the Western US population that winters in California – that the species is likely to survive.

What is threatened with imminent demise is a migration that fascinates scientists and delights people from Canada to Mexico. “We are in danger of losing a great natural phenomenon,” Vidal says. “That should be enough to get us to act.”

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