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The Eastern Monarch Butterflies And The North American Biologists Working To Save Them

On a recent Thursday morning, a few dozen biologists stepped onto a coach bus in a southern borough of Mexico City and headed toward a forest about two hours east. They were traveling to see a colony of species they all study: the eastern monarch butterfly, which migrates every year from Canada, through the United States and into Mexico.

There was an air of optimism in the group. In late January, Mexico’s National Commission for Protected Natural Areas reported the estimated population of eastern monarch butterflies had more than doubled in the previous year, a major reversal from 2014 estimates, when the population was so low it was at risk of extinction. Scientists believe the population bump is due, at least in part, to favorable weather conditions across the butterflies’ path.

"I'm thrilled," said Greg Mitchell, a research scientist with Environment and Climate Change Canada. "This is very good news."

The group of government and university researchers and educators convened in Mexico City for a week to share their work and set priorities for how they can collaborate to help the eastern monarch butterflies thrive. Several said the positive figures only bought them time for conservation efforts. The meeting was organized by the Montreal-based Commission for Environmental Cooperation, which was created by the three North American countries in 1994 after the signing of the North American Free Trade Agreement.

“It is a collaboration and it needs to be,” said Lucie Robidoux, who oversees the commission’s ecosystems unit. “If they maintain the forest where the butterflies hibernate here, but there’s no milkweed for them to feed up north, then the species will not survive.”

Among those on the bus was Sonya Charest, who oversees educational efforts at the Montreal Insectarium. The insect museum began encouraging its visitors to breed monarch butterflies at home in 1992, as a way to help them become acquainted with insects and to help the species grow. Over the years, parents sent the museum photos and videos of tearful children releasing the hatched butterflies, sad to see them leave, Charest said. 

In recent years, the museum discontinued the practice when scientists discovered monarch butterflies raised in captivity were hurting the general population, Charest said.

“It was the most powerful program we had, but the principal objective was to help monarch, and we weren't, so we had to stop,” Charest said. “It was the most difficult decision of my career."

In the forest the biologists visited, called Piedra Herrada in Mexico State, guides from the nearby town of Temascaltepec led them on foot and on horses.

The sanctuary employs about 400 people from the community, and volunteer firefighters patrol the forest, looking to stop fire or illegal logging, two major reasons the trees the monarchs use for wintering disappear, said Rosalío Hernandez, who oversees the sanctuary.

“People are aware that every year, the butterflies are a major benefit to us,” Hernandez said.

The biologists trekked about an hour into the forest to find the butterfly colony. And when they did, they reacted like most tourists do: mouth-open awe of seeing thousands of bright orange butterflies flying across the sky and covering entire tree branches.

When people didn’t talk, the butterflies’ flapping their wings was audible. And something louder: the sound of tree branches cracking under the weight of the butterflies perched on them.

If the butterflies weigh an average of half a gram, there could be more than 10,000 butterflies on each branch, said Isabel Ramirez, a landscape ecologist at the National Autonomous University of Mexico. With the weight of 5 to 10 kilograms, a tree branch could break.

“That's really amazing,” Ramirez said.

After walking out of the forest, Charest said she had held back tears when she saw the colony. She was struck by how peaceful the butterflies looked, and by the long journey they’ve been taking for thousands of years over territory that only relatively recently is three countries, she said.

"I think I'm still emotional a little bit," she said. “Everything is related in nature.”

Seeing the butterflies hibernating reminded Charest that nature has no borders, she said. She added: it confirmed her conviction to tell people to take care of the butterflies’ habitat, from Central Mexico all the way to Montreal.

Jorge Valencia was a senior field correspondent at KJZZ from 2016 to 2019.