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TEHRAN, Jul 22 - Scientists across the country are scrambling to understand why monarch butterflies are disappearing at such an alarming rate as the U.S. Fish and Wildlife Service considers listing the butterfly as endangered.
TEHRAN, Young Journalists Club (YJC) -North America's largest population of monarchs, which migrate between Mexico and the Midwest, has fallen 80 percent, from a billion in the 1990s to 200 million in 2018.
A smaller monarch population in the western United States that migrates between California and the Pacific Northwest is disappearing even faster, dropping from 1.2 million in the 1990s to just 30,000 last year -- a 98 percent drop.
"That is a catastrophic decline," said Tierra Curry, a senior scientist at the Center for Biological Diversity, which is based in Arizona. "They might not be able to bounce back."
Faced with those numbers, the Fish and Wildlife Service is several years into a massive review of North America's butterflies to determine if they qualify for federal protection under the Endangered Species Act.
"We have a species status assessment team that is modeling threat evaluations," said Georgia Parham, a spokeswoman for the Fish and Wildlife Service's Midwest office, which is leading the review.
"We're are also soliciting evaluations from monarch experts, and we've also launched a monarch database that anyone can enter information into," Parham said.
The agency plans to announce its findings in December 2020.
But many scientists say conservation efforts cannot wait that long. Groups like the Center for Biological Diversity, which petitioned the service to list the Monarchs as endangered in 2014, and the Monarch Joint Venture are spearheading conservation programs based on the latest available science.
That science, they are quick to admit, is incomplete.
Scientists cannot say for certain why monarchs are dying. Several unrelated phenomena could be killing them.
"There are several hypotheses for the decline, all of which are probably contributing to some degree," said Andrew Myers is a doctoral student at Michigan State University's Department of Entomology who studies Monarchs.
Finding precise causes are difficult, in part because monarchs are migratory insects.
They clump together on tree branches in the mountains of Mexico to hibernate during the winter -- turning those forests orange. When it warms, they fly north to lay their eggs on milkweed plants growing throughout the Midwest.
They can then travel as far north as Canada in search of the nectar from flowering plants. And when the weather turns cold, they return to Mexico.
Climate change might be disrupting their long migrations, Meyers said. Urban sprawl could be choking out flowering plants. And the Mexican forests in which the insects overwinter are being logged, which undoubtedly is a threat to their survival.
Source: upi
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