Struggle is on to reverse monarch's decline

Jim Lynch
The Detroit News
Monarchs in Mexico in September. Experts say weather and farming habits threaten their numbers.

Brenda Dziedzic caught the bug, or butterfly, early on.

She has fond memories of the fields near where she grew up in Waterford Township teeming with butterflies at a time in her life when she didn't know a black swallowtail from a pearl crescent.

"They always just seemed so beautiful and peaceful," said Dziedzic, 62, who now operates a butterfly habitat in Westland. "When you see them, it just brings a smile to your face."

Smiles have been in shorter supply recently as the population of monarch butterflies, one of the most popular species in the United States, has been in a steep decline in Michigan and across the country. It's a pattern experts believe was caused by a combination of factors and put the future of Danaus plexippus in question.

Monarchs, recognized by their black and orange wings, make an annual appearance in Michigan around late May and early June. They stick around through the year's warmest months and spawn three to five generations before late fall rolls around.

At that point, the last generation packs up and begins moving thousands of miles south toward the central highlands of Mexico. For researchers like Lincoln Brower, that is the place to get the best sense of how the monarch butterflies are faring.

Last week, he remembered seeing the insects' winter homes for the first time in January 1977.

"It was overcast and the butterflies were completely inactive that day," said Brower, a professor of zoology with Sweet Briar College in Virginia. "We walked down through the forest and I suddenly realized the forest had gone from green to completely gray because all of the plants and leaves were covered.

"It was a wall, literally, of monarch butterflies."

At the height of the monarch population during the past 20 years, the butterflies covered 21 hectares or about 52 acres in Mexico during the winter months. (A hectare equals 2.47 acres.) Last year, they covered 0.67 hectares or 1.7 acres — meaning there were an estimated 33 million monarchs in Mexico. That's down from 60 million the year before.

Brower is a leading researcher on these monarch populations, and he says there has been anecdotal evidence that numbers may be slightly up in 2015 from the previous year. The next survey estimate is expected to be released in February or March.

But "even if we double the numbers," Brower said, "we still won't be out of danger."

He lays the blame in three areas:

■Severe weather — record cold years and record hot years, droughts, fires — in both 2012 and 2013 along the butterflies' migratory path killed scores millions of the insects.

■Logging and deforestation in the areas of Mexico that monarch butterflies use as their winter home.

■A widespread agricultural shift in parts of the Midwestern U.S. to use the herbicide Roundup, manufactured by Monsanto, on crops.

Brower points to this last factor as the most dangerous for monarchs because of the placement of these agricultural tracts along the migration route. Roundup kills milkweed, where monarchs typically lay their eggs. It also damages the plants that produce nectar — a major part of their diet.

"Where this kind of agriculture is going on, there is no milkweed anymore," Brower said. As a result, states across the U.S. are seeing fewer and fewer monarchs during the spring and summer months.

Here in Michigan, there have been efforts to spur property owners to plant their own milkweed as a means of offsetting what has been lost to agricultural practices. It's something Dziedzic preaches. "The more little islands of milkweed we can make, the more monarchs we may see," she said. "Otherwise, our grandchildren might not see them up here anymore."