Bob CollinsDespite my best attempts with butterfly gardens and milkweed, the grand total number of Monarch butterflies I saw last summer: 1. It was quite a moment.
That’s not terribly surprising since conservation experts warned us that the number of Monarchs at their Mexico winter home was quite low.
It’s even worse now. This year, the experts announced today, Monarchs cover only 1.65 acres. Last year, they covered almost three acres. In 1995, they covered more than 44 acres.
The chance of seeing a Monarch butterfly in Minnesota this summer is quite low. The Associated Press reports today the annual migration to the south may end forever and the decline of the butterfly is now a long-term statistical trend.
It’s unclear what would happen to the Monarchs if they no longer migrated. The butterflies can apparently survive year-round in warmer climates, but populations in the northern United States and Canada would have to face bitter winters. There is also another small migration route that takes the butterflies to California, but that has also registered declines.
The migration is an inherited trait. No butterfly lives to make the full round-trip, and it is unclear how they remember the route back to the same patch of forest each year, a journey of thousands of miles to a forest reserve that covers 193,000 acres (56,259-hectares) in central Mexico.
Inhabitants of the reserve had already noted a historic change, as early as the Nov. 1-2 Day of the Dead holiday, when the butterflies usually arrive.
“They were part of the landscape of the Day of the Dead, when you could see them flitting around the graveyards,” said Gloria Tavera, the director of the reserve. “This year was the first time in memory that they weren’t there.”
What we did to the bald eagle, we’re doing to the Monarch butterfly. It’s not hard to find the cause, Slate says. There’s the decline of milkweed because more fields are being planted. But there’s also Roundup, because we don’t like weeds more than we do like butterflies.
It’s no coincidence monarchs faltered at the same time. Karen Oberhauser, a conservation biologist at the University of Minnesota, and a colleague estimated that as Monsanto’s Roundup Ready corn and soybeans spread across the Midwest, the amount of milkweed in farm fields fell by more than 80 percent. Oberhauser determined that the loss of milkweed almost exactly mirrored the decline in monarch egg production.
“We have this smoking gun,” Oberhauser said. “This is the only thing that we’ve actually been able to correlate with decreasing monarch numbers.”
Soon there will be essentially no monarchs on cropland in the corn belt, according to some estimates. Already, Iowa farmland has lost more than 98 percent of the milkweed that was once there, according to Iowa State University biologist John Pleasants, who worked with Oberhauser. He’s seen firsthand the transformation as he has studied cornfields during the past decade and a half. Before Roundup, patches of milkweed grew among the corn and along the edges of fields. After the herbicide—nothing but corn.
Related:
- Missing the Monarch butterfly (MPR Statewide).
- Minn. sightings of Monarch butterfly rare as population crashes (Minnesota Sounds and Voices)
