Setting the Table for a Regal Butterfly Comeback, With Milkweed
By MICHAEL WINES
CEDAR FALLS, Iowa — Bounding out of a silver Ford pickup into the single-digit wind-flogged flatness that is Iowa in December, Laura Jackson strode to a thicket of desiccated sticks and plucked a paisley-shaped prize.
It was a pod that, after a gentle squeeze, burst with chocolate brown buttons: seeds of milkweed, the favored — indeed, the only — food of the monarch butterfly caterpillar.
Once wild and common, milkweed has diminished as cropland expansion has drastically cut grasslands and conservation lands. Diminished too is the iconic monarch.
Dr. Jackson, a University of Northern Iowa biologist and director of its Tallgrass Prairie Center, is part of a growing effort to rescue the monarch. Her prairie center not only grows milkweed seeds for the state’s natural resources department, which spreads them in parks and other government lands, but has helped seed thousands of acres statewide with milkweed and other native plants in a broader effort to revive the flora and fauna that once blanketed more than four-fifths of the state.
Nationwide, organizations are working to increase the monarchs’ flagging numbers. At the University of Minnesota, a coalition of nonprofits and government agencies called Monarch Joint Venture is funding research and conservation efforts. At the University of Kansas, Monarch Watch has enlisted supporters to create nearly 7,450 so-called way stations, milkweed-rich backyards and other feeding and breeding spots along migration routes on the East and West Coasts and the Midwest.
But it remains an uphill struggle. The number of monarchs that completed the largest and most arduous migration this fall, from the northern United States and Canada to a mountainside forest in Mexico, dropped precipitously, apparently to the lowest level yet recorded. In 2010 at the University of Northern Iowa, a summertime count in some 100 acres of prairie grasses and flowers turned up 176 monarchs; this year, there were 11.
The decline has no single cause. Drought and bad weather have decimated the monarch during some recent migrations. Illegal logging of its winter home in Mexico has been a constant threat. Some studies conclude that pesticides and fungicides contribute not just to the monarchs’ woes, but to population declines among bees, other butterflies and pollinators in general.
But the greatest threat to the butterfly, most experts agree, is its dwindling habitat in the Midwest and the Great Plains, the vast expanse over which monarchs fly, breed new generations and die during migrations every spring and autumn. Simply put, they say, the flyway’s milkweed may no longer be abundant enough to support the clouds of monarchs of years past.
Soaring demand for corn, spurred by federal requirements that gasoline be laced with corn-based ethanol, has tripled prices in a decade and encouraged farmers to plant even in places once deemed worthless. Since 2007, farmers nationwide have taken more than 17,500 square miles of land out of federal conservation reserves, an Agriculture Department venture that pays growers modest sums to leave land fallow for wildlife. Iowa has lost a quarter of its reserve land; Kansas, nearly 30 percent; South Dakota, half.
A study published in February in the Proceedings of the National Academy of Sciences analyzed land use in five states — Iowa, Minnesota, the Dakotas and Nebraska — in the broad arc of farmland where corn and soybeans are intensively planted. Over the five years from 2006 to 2011, the study concluded, 5 percent to 30 percent of the grasslands were converted to corn and soybean fields, a rate it said was “comparable to deforestation rates in Brazil, Malaysia and Indonesia.”
At the same time, farmers have switched in droves to new varieties of crops that are genetically engineered to tolerate the most widely used weed killer in the United States. The resulting use of weed killers has wiped out much of the milkweed that once grew between crop rows and on buffer strips separating fields and roads.
Roughly half of all Mexico-bound monarchs are hatched in the Midwest and depend as caterpillars on milkweed for food, according to a 2012 study that concluded that the region lost 58 percent of its milkweed and 81 percent of its monarchs between 1999 and 2010.
Said Dr. Jackson, “I can drive five hours east, five hours north, five hours south, five hours west and see nothing — nothing — but corn and soybeans.”
Beleaguered as they are, the butterflies do have one advantage: their seemingly unmatched popularity. Scientists allow that neither the butterfly nor its migration is crucial to the balance of nature. But as rallying points for conservationists and early warning signals of environmental problems, they are invaluable, backers say.
Monarch Watch’s director, Chip Taylor, decided last spring to sell milkweed “plugs” to supporters, charging $58 for a flat of 32 plants — and sold 22,000. The Natural Resources Defense Council gave him a grant this month to supply still more to 100 schools. Even the crowdfunding website Kickstarter sports a proposal to rally monarch support through an arts program.
There is no shortage of ideas. The Pollinator Partnership, a San Francisco-based organization, is pushing for federal legislation that would encourage more state highway departments to stop mowing roadsides and plant bee-friendly wildflowers and monarch habitat instead. (Some states, including Iowa, Texas and Minnesota, already plant some medians and shoulders.)
Next month, the group will publish a booklet showing utility companies how to establish monarch habitats under their power line rights-of-way. The organization’s executive director, Laurie Davies Adams, promoted aid to monarchs before the Wildlife Habitat Council, a consortium of major corporations involved in environmental stewardship.
“This is the Fortune 500 — big manufacturing and mining concerns,” she said in an interview. “I talked about pollinators and monarchs specifically, and they get it. But nobody’s acting yet.”
A few have stepped forward. Chevron added monarch habitat several years ago to a 500-acre stretch of native wetlands and prairie it maintains on an old refinery site 20 miles west of Cincinnati. Waste Management Inc. includes butterfly-friendly plantings on scores of capped landfills around the nation.
Dr. Taylor, of Monarch Watch, said he was convinced that the annual migration to Mexico can be revived; butterfly populations, he said, can fluctuate wildly from year to year as weather and habitat change. The insect’s troubles probably were as deep, or deeper, during the Dust Bowl of the 1930s, he said. But so far, he said, monarch backers are mostly preaching to the choir, “and the choir’s of limited size.”
Northern Iowa’s Dr. Jackson said it would take a much larger — and speedier — effort to undo the impact of thousands of square miles of habitat loss.
“Monarchs are just like other iconic species,” she said. “Once people stop being accustomed to seeing them, they stop caring and they forget. Support drops like a ratchet.”
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