Sweet Briar research biologist Lincoln Brower’s most recent trip to observe overwintering monarch butterflies in central Mexico included rewarding highs and distressing lows.
The renowned monarch expert spent the first day, Feb. 17, with President Jimmy Carter — whose attentive company helped account for the high points. Carter had arranged to visit a butterfly colony with Brower and was waiting for him when he and his colleagues arrived at the site on horseback. It was the beginning of a memorable day, Brower said.
Carter was prepared, having read the research papers Brower sent ahead. He peppered him with incisive questions and asked why so few of the migratory monarchs had reached their winter habitat this year. That stark reality was the root of Brower’s distress during the course of the trip.
On March 13, the World Wildlife Fund Mexico released its annual monarch census, confirming their numbers are down by 59 percent over last year. That’s the smallest population since record keeping began 20 years ago, measured by the total area of forest occupied by the insects each season.
Among the culprits, Brower told Carter, is the prevalence of corn and soybean crops that are genetically engineered to resist herbicides. The chemicals destroy native flora, including milkweed — the butterflies’ food in spring and summer. Genetically modified plants, known as GMOs, are “eliminating milkweed and nectaring habitats on an unprecedented scale where most of the monarchs breed in the Midwestern United States,” Brower says.
Carter defended their use, however. “He told me that cotton growing on his farm in Georgia had been overwhelmed by the boll weevil and required multiple sprayings until GMO weevil-resistant plants were introduced,” Brower said. “So he emphasized that balance is needed.”
Nor is Brower blaming the monarch’s decade-long decline on a single cause. He describes what he saw en route to and from the colony site in a trip report:
We ascended the mountain in swirling clouds of dust and the heavy horse and tourist impact has led to extensive elimination of understory vegetation along the trail and adjacent to the colony. We also noticed the installation of a plastic water pipe draining water away from the colony, depriving the butterflies of critical moisture.
On our return to the visitor center, we passed more than 50 horses and noted 24 huge passenger buses parked nearby. An official sign along the trail stated that there is a limit of 20 visitors at a time to the colony. In violation of their own edict, hugely excessive numbers of tourists are visiting this monarch butterfly overwintering colony.
Every year, the black and orange monarchs pull off one of the great migrations of the natural world, a brand-new generation arriving from thousands of miles away in a place where precise conditions meet their survival needs. At night they roost in oyamel fir trees by the millions; in the warmth of the day, they stream en masse to nearby water sources. Even small changes to the microclimate, such as those caused by selective illegal logging and out-of-control ecotourism, make freezing and starvation more likely.
Following the February trip, Brower and a fellow conservationist, Homero Aridjis, wrote an op-ed for The New York Times outlining multiple causes for the monarch’s imperiled state and urging shared responsibility for addressing them. In “The Winter of the Monarch,” Brower and Aridjis argue that continued illegal logging in the wintering grounds is a threat equal to the destruction of breeding habitat in the north, despite the WWF Mexico’s claim that Mexico has done its part by eradicating large-scale deforestation.
The monarch’s plight and Brower’s position have been widely reported by The New York Times, The Guardian and in an Associated Press story that was picked by up outlets from the Washington Post to Al Jazeera.
Brower saw ample evidence of illegal logging during the rest of his research trip, but his time with the president didn’t end with the colony visit. At the villa where the Carters were staying, he and his fellow scientists presented short slide presentations on their conservation and research activities. Again, the president asked informed and insightful questions.
The dinner conversation that evening sparkled, he said. Sitting next to one another, the two men discussed everything from Carter’s youth in Plains, Ga., to his disease-prevention work in Africa to recent Supreme Court decisions.
“It was a highlight of my life,” Brower said.